Energy Technology Data Exchange (ETDEWEB)

The oxidation of sulfur dioxide in gas diffusion electrodes (GDE) in the presence of a homogeneous catalyst, potassium iodide, is investigated. The influence of this catalyst on the voltage-current (V-I) characteristics of the electrodes and the utilization of sulfur dioxide is determined. It is shown that when using the homogeneous catalyst potassium iodide, the utilization can reach 95-100%.

Energy Technology Data Exchange (ETDEWEB)

To develop oxygen electrodes for rechargeable metal-air batteries, the electrochemical behaviour of gas-diffusion-type carbon electrodes loaded with Pr-Mn-Fe-based perovskite-type oxides was examined for the reduction and evolution of oxygen in 8 M KOH at 60 C. Among the oxides tested, Pr{sub 0.2}Ca{sub 0.8}Mn{sub 0.1}Fe{sub 0.9}O{sub 3} gave the highest electrode performances, e.g., current densities of 275 mA/cm{sup 2} (for oxygen reduction) and 225 mA/cm{sup 2} (for oxygen evolution) at -300 and +650 mV vs. Hg/HgO, respectively. The electrode performances were found to depend on both the catalytic activity of the oxides for H{sub 2}O{sub 2} decomposition reaction and the amounts of oxygen desorbed from the oxides. Furthermore, it was confirmed that the small zinc-air battery including the gas-diffusion-type electrode loaded with Pr{sub ...

Energy Technology Data Exchange (ETDEWEB)

Thin, lightweight, and flexible gas-diffusion electrodes (GDEs) based on freestanding entangled networks of single-walled carbon nanotubes (SWNTs) decorated with Ag nanoparticles (AgNPs) are tested as the air-breathing cathode in a zinc-air battery. The SWNT networks provide a highly porous surface for active oxygen absorption and diffusion. The high conductivity of SWNTs coupled with the catalytic activity of AgNPs for oxygen reduction leads to an improvement in the performance of the zinc-air cell. By modulating the pH value and the reaction time, different sizes of AgNPs are decorated uniformly on the SWNTs, as revealed by transmission electron microscopy and powder X-ray diffraction. AgNPs with sizes of 3-5 nm double the capacity and specific energy of a zinc-air battery as compared with bare SWNTs. The simplified, lightweight architecture shows significant advantages over conventional carbon-based GDEs in terms of ...

Energy Technology Data Exchange (ETDEWEB)

Studies are made on electrode behaviors of hydride ion in eutectic LiCl-KCl molten salt by various electrochemical methods. As a result, it is confirmed and clarified, by cyclic voltammetry, that anode reaction of hydride ion exists and it is a diffusion-controlled, reversible and one-electron reaction. Also, generation of hydrogen gas is confirmed by a potentiostatic electrolysis, and the electrolysis in the current efficiency of about 95% is possible by controlling electric potential. Moreover, results of chronopotentiometry and chronoamperometry show that hydride ion is anodically oxidized by the diffusion controlling reaction and the reaction itself is reversible. Results of cyclic voltammetry indicate that a diffusion constant D{sub H} {sup {minus}} equals 3.0 {times}10 {sup {minus}5}cm{sup 2}{center dot}S{sup {minus}1} (425 centigrade). This value corresponds well to the ...

International Nuclear Information System (INIS)

Ultra low loading noble metal (0.04-0.12 mg_P_t/cm"2) based electrodes were obtained by direct metallization of non-catalyzed gas diffusion layers via dual ion beam assisted deposition (IBAD) method. Fuel cell performance results reported earlier indicate significant improvements in terms of mass specific power density of 0.297 g_P_t/kW with 250 A thick IBAD deposit (0.04 mg_P_t/cm"2 for a total MEA loading of 0.08 mg_P_t/cm"2) at 0.65 V in contrast to the state of the art power density of 1.18 g_P_t/kW using 1 mg_P_t_(_M_E_A_)/cm"2 at 0.65 V. In this article we report the peroxide radical initiated attack of the membrane electrode assembly utilizing IBAD electrodes in comparison to commercially available E-TEK (now BASF Fuel Cell GmbH) electrodes and find the pathway of membrane degradation as well. A novel segmented fuel cell is used for this purpose to relate ...

Energy Technology Data Exchange (ETDEWEB)

Three studies of electrochemical current distribution have been performed using potential-theory models and the boundary-element method (BEM). (1) The steady-state behavior of cells with nonuniform current density over a passivating anode is investigated. Current distributions calculated for a test cell, using the measured kinetic behavior of nickel in acid-nickel-sulfate solution, are compared to estimates from earlier models. Although current-density profiles determined by weight loss on a segmented rotating cylinder agreed satisfactorily with model calculations, the measured length of the passive zone exceeds the theoretical value. The model's applicability to anodic protection is demonstrated for a stainless-steel sulfuric-acid holding tank. (2) A model is established to describe the effects of attached bubbles on the potential drop at gas-evolving electrodes including: (1) ohmic obstruction within the electrolyte; (2) area masking ...

Energy Technology Data Exchange (ETDEWEB)

Single-electrode transient behavior was measured mainly during the discharging process for a model cell of electric double layer capacitor with nano-porous carbon electrodes and reference electrode. Apparent conductivity in the cell, which we call `effective conductivity,` is determined with approximation of current in transient behavior to a one-dimensional electrophoretic model. A comparison of effective conductivity with conductivity of bulk solution suggests an interesting mechanism of transfer of electrolyte ions. The difference in transient behavior between various electrolyte ions was not conspicuous in spite of distinctive differences in conductivity of each bulk solution. The large pore diameter of the carbon electrode results in rapid transient behavior and such an electrode should be suitable for rapid charge and discharge. The effect of origin of carbon ...

Energy Technology Data Exchange (ETDEWEB)

An improved ion funnel design is disclosed that decreases the axial RF (parasite) fields at the ion funnel exit. This is achieved by addition of one or more compensation electrodes after the conductance limit electrode. Various RF voltage profiles may be applied to the various electrodes minimizing the parasite axial potential wells. The smallest RF aperture that serves as the conductance limiting electrode is further reduced over standard designs. Overall, the ion funnel improves transmission ranges of both low m/z and high m/z ions, reducing RF activation of ions and decreasing the gas load to subsequent differential pumping stages.

Energy Technology Data Exchange (ETDEWEB)

Part of the crushed activated charcoal (about 20-50%) designed for manufacture of electrodes is made water repellant with the help of an aqueous suspension of water repelling agent containing 3-15% (preferably 10%) dry substance. After this the remaining part of the activated charcoal and the other additives are mixed with the water repelling part. The plates or tape which is rolled to an assigned thickness are pressed from the obtained mixture. The electrodes obtained by this method have a thin active layer and a porous structure and have good diffusion properties. They can be loaded by currents up to 80 mA/cm/sup 2/ without causing excessive polarization losses, and their service life is greater than or equal to 100 h.

Science.gov (United States)

In this paper, a novel type of a corona discharge plasma reactor was designed, which consists of needle-plate-combined electrodes, in which a series of needle electrodes are placed in a glass container filled with flue gas, and a plate electrode is immersed in the water. Based on this model, the removal of NO and SO2 was tested experimentally. In addition, the effect of streamer polarity on the reduction of SO2 and NO was investigated in detail. The experimental results show that the corona wind formed between the high-voltage needle electrode and the water by corona discharge enhances the cleaning efficiency of the flue gas because of the presence of water, and the cleaning efficiency will increase with the increase of applied dc voltage within a definite range. The removal efficiency of SO2 up to 98%, and about 85% of NOx removal under suitable conditions is ...

Energy Technology Data Exchange (ETDEWEB)

Because of its high energy density, compatibility with aqueous electrolytes and the low toxicity of its active materials, the zinc-air battery system is an interesting candidate for electric vehicle applications. The use of O{sub 2} from the air as a reactant requires a partially open cell construction and a technologically challenging air interface. This report describes the research and development program at the Paul Scherrer Institute which finally led to the demonstration of a durable, electrically rechargeable zinc-oxygen battery. In a first phase the research program was focused on the development of bifunctional oxygen diffusion electrodes and pasted zinc electrodes. The current-potential behaviour and the cycle life performance of anodes and cathodes was tested in single electrode measurements (three-electrode arrangements) as well as in complete monopolar zinc-oxygen and ...

Energy Technology Data Exchange (ETDEWEB)

The development of a gas-operated diffusion absorption heat pump for the heating of living spaces is described. By various improvement an energy efficiency of the prototypes of 1.5 was achieved. Structural alterations led to a lower overall height and lower production costs. The CFCs used in electric heat pumps were replaced by environmentally neutral ammonia. Compared with conventional gas heating systems, the CO2 output could be reduced by more than 30%. figs., tabs.

Energy Technology Data Exchange (ETDEWEB)

The effect of the composition of multicomponent Zr-Ti-V-Mn-Cr-Ni alloys on their hydrogen-storage capacity and on the rate of electrosorption/desorption hydrogen was investigated under potentiodynamics as well as single-pulse and long-term galvanostatic conditions. The main characteristics of alloys and alloy electrodes were determined by their structural analysis by means of X-ray diffraction and scanning electron microscope, by specific surface area test and by determination of the hydrogen absorption/desorption isotherms in the gas/solid phase system. It was found that only the alloys with a manganese content below a threshold could be used as electrode materials for Ni-MH batteries, whereas the modification of the electrode material by micro-encapsulation of alloy particles should limit the dissolution of manganese from the electrode material in a strong alkaline solution. ...

Science.gov (United States)

Results are reported from studies of the diffusion rate of xenon through frog abdominal skin and toad urinary bladders, typical epithelial membranes. It was concluded that intracellular water serves as the principal barrier for xenon passage through epithelial tissue.

Science.gov (United States)

This paper discusses the mechanisms of gas breakdown at low values of pressure and inter-electrode gap, i.e. in the vicinity of the Paschen minimum. In this area of pressure and inter-electrode gap values, breakdown occurs either through gas or vacuum mechanisms, and also the so called anomalous Paschen effect appears. Electrical breakdown of electropositive, electronegative and noble gases has been investigated theoretically, experimentally and numerically. Based on the results obtained, regions in which particular breakdown mechanisms appear have been demarcated. Special attention has been devoted to the anomalous Paschen effect as well as to the avalanche vacuum breakdown mechanism.

International Nuclear Information System (INIS)

Short-lived fission gas release from fuel pellets during irradiation was investigated based on the experimental results of the gas-flow rigs irradiated in the Halden Heavy Water Reactor (HBWR). The release-to-birth (R/B) rates of short-lived fission gas were measured by means of gas-flow measurement during the irradiation experiments. Surface-to-volume (S/V) ratios of fuel pellets and diffusion coefficients of short-lived fission gas release were evaluated from the obtained (R/B) values. The increase of (S/V) ratio agreed well with the point where the fuel temperature exceeded the threshold of 1% fission gas release. This indicates that the interlinkage of fission gas bubbles occurred there. The evaluated diffusion coefficients scattered in the range between 10"-"2"3 and 10"-"1"7 m"2/s, and the ...

UK PubMed Central (United Kingdom)

Gas exchange between the plant and the environment is severely hampered when plants are submerged, leading to oxygen and energy deficits. A straightforward way to reduce these shortages of oxygen and...Full Text Available

Energy Technology Data Exchange (ETDEWEB)

New results for two types of nano-size silicon, prepared via thermal vapour deposition either with or without a graphite substrate are presented. Their superior reversible charge capacity and cycle life as negative electrode material for lithium-ion batteries have already been shown in previous work. Here the lithiation reaction of the materials is investigated more closely via different electrochemical in situ techniques: Raman spectroscopy, dilatometry and differential electrochemical mass spectrometry (DEMS). The Si/graphite compound material shows relatively high kinetics upon discharge. The moderate relative volume change and low gas evolution of the nano silicon based electrode, both being important points for a possible future use in real batteries, are discussed with respect to a standard graphite electrode. (author)

British Library Electronic Table of Contents (United Kingdom)

The electroreduction process of Zr(IV) was studied at molybdenum electrode in LiCl-KCl-K2ZrF6 molten salt. The transient electrochemical techniques, such as cyclic voltammetry and chronopotenimetry were used. The experimental results showed that the electrochemical reduction of Zr(II)/Zr and Zr(IV)/Zr(II) were both diffusion-controlled process. In the 773-973K range, the diffusion coefficients of Zr(ii) and Zr(IV) were determined: DZr(II)=0.15567exp{-69.65x10^3RT(K)}cm^2/s, DZr(IV)=1.09x10^-^4exp{-44.39x10^3RT(K)}cm^2/s. The activation energy values for the diffusion process were 69.65kJ/mol and 44.39kJ/mol, respectively.

Science.gov (United States)

The entrainment flow rate distribution, the gas velocity profile, and the concentration profile of droplets across the channel cross section in fully developed region of a horizontal rectangular channel of 150mm width and 50mm height were measured. The concentration profile of droplets was expressed by a simple equation based on a constant diffusion coefficient model. From this equation the effects of gravity and turbulent diffusion of droplets on the concentration profile were evaluated. The characteristic mean settling velocity of a group of droplets with various diameters was derived, and using this value the mean diffusion coefficient of the group of droplets was obtained

Energy Technology Data Exchange (ETDEWEB)

In the present study, element interdiffusions at the cofired interface of 9/1 Ag/Pd electrode and lead magnesium niobate (PMN)-based ferroelectrics were investigated using Auger Electron Spectroscopy (AES). Intense interdiffusions at the interface were observed while Ag and Pd could penetrate into the ceramics for about 1 {mu}m. Ag-doping experiments were carried out to further study the effects of Ag diffusion on electrical properties of the ceramics. The results showed that Ag could be incorporated into solid solution of the ceramics as Ag{sup +}. As a whole, the Curie temperature (Tc) and dielectric constant of the ceramics decreased with Ag addition. However, Ag addition had no obvious effect on the insulation resistivity. The results inferred that Ag{sup +} could substitute for Pb{sup 2+} at A site of ABO{sub 3} lattice, thereby oxygen vacancies were generated.

Energy Technology Data Exchange (ETDEWEB)

Uranium enrichment by gas centrifugation relies on the pressure diffusion of the isotopes when their gaseous mixture is submitted to the pressure diffusion in the strong radial pressure gradient due to the centrifugal force in a very rapidly rotating cylinder. To compute the isotope separation in a gas centrifuge, the viscous compressible Navier-Stokes equations are solved for the mixture, then the diffusion equations are solved for the isotopes. As far as the separation performance is concerned, the models deal with the steady state of the axi-symmetric gas motion in the rotating cylinder. The numerical tools are briefly presented: first, the MOLINA code which numerically solves the axi-symmetric gas motion in the specific conditions of rapid rotation by use of a change of variables suited to the high density gradient and by use of a Marker ...

Energy Technology Data Exchange (ETDEWEB)

A new technique for ion implantation into concave surface of insulating materials is proposed and experimentally studied. The principle is roughly described by referring to modifying inner surface of a PET (polyethylene terephthalate) bottle. An electrode that is supplied with positive high-voltage pulses is inserted into the bottle. Both plasma formation and ion implantation are simultaneously realized by the same high-voltage pulses. Ion sheath with a certain thickness that depends on plasma parameters is formed just on the inner surface of the bottle. Since the plasma potential is very close to that of the electrode, ions from the plasma are accelerated in the sheath and implanted perpendicularly into the bottle's inner surface. Laser Raman spectroscopy shows that the inner surface of an ion-implanted PET bottle is modified into DLC (diamond-like carbon). Gas permeation measurement shows that ...

Science.gov (United States)

The Energy crisis happens to be one of the greatest challenges we are facing today. In this view, much effort has been made in developing new, cost effective, environmentally friendly energy conversion and storage devices. The performance of such devices is fundamentally related to material properties. Hence, innovative materials engineering is important in solving the energy crisis problem. One such innovation in materials engineering is porous materials for energy storage. Porous electrode materials for lithium-ion batteries (LIBs) offer a high degree of electrolyte-electrode wettability, thus enhancing the electrochemical activity within the material. Among the porous materials, mesoporous materials draw special attention, owing to shorter diffusion lengths for Li+ and electronic movement. Nanostructured mesoporous materials also offer better packing density compared to their nanostructured counterparts such as ...

International Nuclear Information System (INIS)

A cross-flow atmospheric plasma jet with distilled water or analyte solution nebulization has been investigated. The plasma gas flows perpendicularly to the RF powered electrode (11.21 MHz) and a grounded electrode was added for plasma stabilization. The working parameters of the plasma generator can be controlled in order to maximize either the plasma power (75 W) or the voltage on the RF powered electrode (plasma power, 40 W). The plasma gas, pure argon (0.4 l min-1) or a mixture of argon (0.3-0.4 l min-1) and helium (0-0.2 l min-1), was also used for liquid nebulization. Optical emission of the plasma, collected in the normal viewing mode, was used for plasma diagnostics and for evaluating its excitation capabilities. The influence of helium content in the mixed-gas plasma on the plasma characteristics and on the emission axial profiles of the plasma ...

British Library Electronic Table of Contents (United Kingdom)

Porous SnO2 nanotubes were prepared via electrospinning followed by calcination in air. As anode materials for lithium ion batteries, the porous nanotubes delivered a high discharge capacity of 807mAhg^-^1 after 50cycles. Even after cycled at high rates, the electrode still retained a high fraction of its theoretical capacity. Such excellent performances of porous SnO2 nanotubes could be attributed to the porous and hollow structure which facilitated liquid electrolyte diffusion into the bulk materials and buffered large volume changes during lithium ions insertion/extraction. Furthermore, the nanoparticles of nanotubes provided the shorter diffusion length for lithium ions insertion which benefited in retaining the structural stability and good rate performance. Our results demonstrated t...

Energy Technology Data Exchange (ETDEWEB)

A new article identification method based on the measurement of Bragg-curve centroids using a gas-filled ionization chamber has been improved for detection of low-energy particles around 1 MeV per nucleon by introducing a nonuniform distribution of resistance on the anode electrode. Almost the same quality of Z-resolutions as in the conventional ..delta..E-E method could be obtained up to Z=19.

International Nuclear Information System (INIS)

Most diffusion phenomena in solids can be understood (or sometimes misunderstood) on a purely classical model. For light interstitials (hydrogen isotopes, the positive muon, and potentially He) there may be anomalous temperature dependences, and isotope effects, and anomalous response to electric fields and temperature gradients. Some of these anomalies are quantal in origin, and will be discussed. (author).

International Nuclear Information System (INIS)

The presence of an extraneous light gas must be taken into account in consideration of centrifugal separation of uranium isotopes, when there is inevitable leakage of such a gas through the gas sealant and/or leaking in from the atmosphere. Consideration is first given to the influence of the presence of the light gas on the maximum separative power. Then the basic equation for isotope separation containing a light gas is derived from Hirschfelder's diffusion equations. This equation is solved and the separative performance is expressed in terms of the shape factor and reflux parameter. The formulas for expressing the flow configurations of the gases are obtained for a simple model in which inflow and outflow prevail throughout the centrifuge. The corresponding equation for a model in which the gases flow in two concentric thin streams is also derived. It is ...

Energy Technology Data Exchange (ETDEWEB)

Results of experiments performed utilizing high-power microwave sources for laser-discharge switching and preionization are reported. These results are not definitive, but are promising. Significant preionization using microwaves is possible. Some ability to switch the discharge and operate a laser have been demonstrated. More work needs to be performed to perfect the microwave coupling to the laser mixture. In particular, experiments with the microwaves better concentrated between the electrodes should be performed. The best way to accomplish this appears to be using the side-feed geometry; however, a large expansion of the microwaves should occur (to well below the power able to break down the window), and then a cylindrical lens should be used to focus the microwaves between the electrodes. 2 references.

Energy Technology Data Exchange (ETDEWEB)

MCrAlY coatings are widely used on hot section components of gas turbines to provide hot corrosion and/or oxidation protection by formation of an oxide layer on the surface. As the protective oxide scale exfoliates during service, aluminum from the coating diffuses outward for reformation of the protective scale. Aluminum may also diffuse inward due to the differences in composition between the coating and the substrate. Thus, the coatings degrade due to oxidation, oxide scale spallation, and inward and outward diffusion of aluminum. Service life of these coatings is controlled by the aluminum content in the coating, operating temperature and start- shutdown cycles. In-service degradation of CoCrAlY and CoNiCrAlY coatings is presented. A procedure to predict the remaining service life of coatings under oxidizing conditions is discussed. (orig.) 12 refs.

International Nuclear Information System (INIS)

The nature of the electrolyte strongly influences the electrode kinetics of the oxygen evolution reaction (OER) and electrochemical ozone production (EOP) mainly by affecting the degree of coverage by the intermediates of both processes. The anomalous behaviour of the Tafel coefficient, b, as a function of temperature was attributed to surface adsorption of the electrolyte species, and the competition between them, as well as gas bubble adherence. Comparison of the current efficiencies of the EOP, PHI_E_O_P, determined for different temperatures and supporting electrolyte compositions, showed the presence of fluorinated anions increases PHI_E_O_P. The influence of the anion nature on PHI_E_O_P, when analysed in the light of the proposed electrode mechanism, reveals introduction into the electrolyte of anions having a high electronegativity changes the double layer structure resulting in an increase of surface concentration ...

Energy Technology Data Exchange (ETDEWEB)

Correlation between mechanical stress and hydrogen effects on radiation damage in polycide-gate MOS capacitors was investigated as a function of gate-oxide thickness. The compressive stress magnitude was altered by varying the silicide (TiSi/sub 2/ or WSi/sub 2/) thickness in the polycide-gate electrode, and hydrogen introduction into gate-SiO/sub 2/ film was carried out by diffusion from plasma-deposited silicon-nitride passivation film (SiN-Cap). In a MOS capacitor without passivation film (No-Cap sample), it was found that compressive stress on gate-SiO/sub 2/ reduces both positive charge build-up (..delta..Qot) and interface-trap generation (..delta..Dit). Radiation induced shift, ..delta..Qot exhibits a smaller stress effect as compared with ..delta..Dit. As gate-SiO/sub 2/ thickness decreases, the stress effect on ..delta..Qot increases, while this effect on ..delta..Dit remains nearly constant. This compressive stress effect was ...

Energy Technology Data Exchange (ETDEWEB)

In order to overcome the inherent disadvantages of Ti-V-based hydrogen storage alloys, such as poor activation behavior and low high-rate dischargeability, the novel composites Ti{sub 0.17}Zr{sub 0.08}V{sub 0.35}Cr{sub 0.1}Ni{sub 0.3}-x wt.% La{sub 0.7}Mg{sub 0.3}Ni{sub 2.75}Co{sub 0.75} (x = 0, 5, 10 and 20) were successfully synthesized by ball milling method in the present study. And the structure and overall electrochemical properties of as-prepared composites are investigated systemically. The electrochemical studies show that the maximum discharge capacity of the composite electrodes displays no variation with the increase of La{sub 0.7}Mg{sub 0.3}Ni{sub 2.75}Co{sub 0.75} content, whereas the high-rate dischargeability (HRD) and the activation behavior are distinctly improved with increasing x. The electrochemical hydrogen kinetics of composite electrodes is also studied by means of electrochemical impedance spectroscopy (EIS), linear ...

Energy Technology Data Exchange (ETDEWEB)

In this paper coating developments for advanced gas turbine engines (diffusion aluminide coatings, overlay coatings, and ceramic thermal barrier coatings) were desorbed, a selection of current metallic coatings was made and their performance as outlined. Finally coating developments for advanced diesel engines with a view to improved turbocharging or to low heat rejection engines (adiabatic diesel concept) were dealt with. (IHOE).

Energy Technology Data Exchange (ETDEWEB)

The purpose of this study is to identify the radiative heat transfer augmentation by a coaxial cylinder introduced in the infinite cylindrical pipe enclosing a participating gas. The gas is either a mixture of water vapor and carbon dioxide or gray. The gas is assumed to be homogeneous at a constant temperature, and has a refractive index of unity. All of the surfaces are opaque and gray, diffusely emitting and reflecting at a constant temperature. The effect of system diameter, diameter ratio, wall emittances, gas and surface temperatures, mixture component on heat transfer augmentation are studied by using the zone method with participating gas radiative properties evaluated from the weighted sum of gray gases model. From the radiative equilibrium condition, the installed wall temperature is formulated and calculated by the iteration method. If the medium is a ...

Energy Technology Data Exchange (ETDEWEB)

Grout has been evaluated as a means of containing low-level radioactive waste for long-term disposal. Concerns about hydrogen and reactive gas generation in the Hanford Site grout disposal facility lead to the development of the G3 model, which has predicted buildup of radiolytically formed gases in the grout region and their migration to air-filled regions. The G3 model is a one-dimensional code that couples models of gas diffusion with two-phase gas and liquid flow. It was coupled to a compartment diffusion model and these models predicted the concentrations of hydrogen I nitrous oxide, and other gases in air-filled regions of the grout disposal facility. The results have served as the technical basis for safety studies. A unique finding of the G3 model was that a liquid return, or expulsion of unbound liquid from the grout region, could occur. This liquid return is driven by ...

International Nuclear Information System (INIS)

AISI 5140 steel was plasma nitrided at various gas mixtures of nitrogen, hydrogen, and argon to investigate the actions of hydrogen and argon on plasma nitriding. The structural and mechanical properties of ion-nitrided AISI 5140 steel have been assessed by evaluating composition of phases, surface hardness, compound layer thickness, and case depth by using X-ray diffraction (XRD), microhardness tests, and scanning electron microscopy (SEM). It was found that the growth of compound layer can be controlled and the diffusion improved when the gas mixture includes H_2 gas. Additionally, it was determined that the amount of Ar in dual gas mixture must be at 20% minimum to obtain distinctive surface hardness and compound layer thickness.

Science.gov (United States)

A number of agricultural and engineering uses for fixated flue gas desulfurization (FGD) material exist; however, the potential for leaching of hazardous elements has limited widespread application and the processes controlling the leaching of this material are poorly understood. In this study, a flow-through rotating-disk system was applied to elucidate the relative importance of bulk diffusion, pore diffusion, and surface chemical reaction in controlling the leaching of fixated FGD material under pH conditions ranging from 2.2 to 6.8. Changing the hydrodynamics in the rotating disk system did not affect the leaching kinetics at both pH 2.2 and 6.8, indicating that bulk diffusion was not the kinetic-limiting step. Application of the shrinking core model (SCM) to the data suggested a surface reaction-controlled mechanism, rather than a pore diffusion mechanism. The leaching of ...

Energy Technology Data Exchange (ETDEWEB)

Membranes in Palladium and its alloys, in particular Pd/Ag alloys, are selectively permeable to hydrogen and can therefore be used to purify hydrogen. It is intended to use them as material for electrodes in fuel cells. As the manufacturing process of a substrate Pd/Ag-layer consists of several stages and is still not completely understood, it would be advantageous to be able to characterise separately the layers of noble metals obtained by electro-plating . Attempts are being made in this work to vary the cristallographical structure of the deposited alloy by the choice of test parameters and by sintering when depositing the Pd/Ag. The layers produced are to be examined using an interference microscope and X-ray diffraction. Moreover, the diffusion behaviour of the hydrogen is to be examined with an electro-chemical pulse method specifically developed for this purpose. figs., tabs., 27 refs.

CERN Document Server

In this paper we develop an analytical framework for the study of electrochemical impedance of mixed ionic and electronic conductors (MIEC). The framework is based on first-principles and it features the coupling of electrochemical reactions, surface transport and bulk transport processes. We utilize this work to analyze two dimensional systems relevant for fuel cell science via finite element method (FEM). Alternate current Impedance Spectroscopy (IS) of a ceria symmetric cell is simulated near equilibrium condition (zero bias) for a wide array of working conditions including variations of temperature and $H_2$ partial pressure on a two dimensional fuel cell sample with patterned metal electrodes. The model shows agreement of IS curves with the experimental literature with the relative error on the impedance being consistently below 2%. Important two-dimensional effects such the effects of thickness decrease and the influence of variable electronic and ionic ...

British Library Electronic Table of Contents (United Kingdom)

The kinetics of the electropolymerization of 3-amino-1,2,4-triazole on a brass substrate in alkaline solution containing methanol was investigated using cyclic polarization, chronoamperometry, electrochemical impedance techniques and scanning electronic microscopy. The polymeric film was prepared by successive cycles of potential of a 60Cu-Zn electrode between 0 and 1.6V. During the second cycle, the oxidation peak of the monomer disappears indicating the formation of the insulating film. We have also shown that the monomer oxidation reaction is essentially irreversible and controlled by a diffusion process. The protective effect of the film formed on brass has been studied in a 3%NaCl and 3%NaCl+S2- solution. The results showed important inhibition efficiency, about 96% for 4h of testing ...

British Library Electronic Table of Contents (United Kingdom)

The electrochemical behavior of Sb(III) ions was investigated in LiCl-KCl molten salt at 673K. The reaction mechanism and transport parameters of electroactive species were determined by transient electrochemical techniques (such as cyclic voltammetry, square wave voltammetry, chronopotentiometry and chronoamperometry) at a molybdenum electrode. The results showed that electrochemical reduction of Sb(III) in LiCl-KCl melts occurred in a reaction step with an exchange of three electrons. A voltammogram with a different scan rate in LiCl-KCl containing 1.45x10^-^4molcm^-^3 SbCl3 showed that the deposition/dissolution reaction of Sb(III) ions was not completely reversible. The diffusion coefficient of Sb(III) ions was 1.65(+/-0.01)x10^-^5cm^-^2s^-^1 at 673K. The electroreduction of Sb(III) io...

International Nuclear Information System (INIS)

Cr_2O_3 scales are found to form on Alloy 800 and a similar pure ternary alloy in air, and 1 and 50 atm. helium containing oxidizing impurities typical of those in an SGHTR. The strong temperature dependence and neglibible helium overpressure dependence indicate that gas transport through the scales is not rate controlling. Surface oxidation rates are therefore controlled by solid state diffusion and the low oxygen partial pressure dependence of the oxidation rate in Alloy 800 is ascribed to the presence of extrinsic defects in the Cr_3O_3 (due to doping by alloying elements) or to the presence of short circuit diffusion paths. (Auth.).

Energy Technology Data Exchange (ETDEWEB)

Measurements of the expansion rate of pure-electron plasmas have been performed on the Electron Diffusion Gauge (EDG) device at background helium gas pressures in the 5 x 10(superscript -8) Torr to 1 x 10(superscript -5) Torr range, where plasma expansion due to electron-neutral collisions dominates over plasma expansion due to trap asymmetries. It is found that the expansion rate, defined as the time rate of change of the particles' mean-square radius, scales approximately linearly with pressure and inversely as the square of the magnetic field strength in this regime, in agreement with classical predictions.

International Nuclear Information System (INIS)

In this paper, we propose to characterize boron transient enhanced diffusion (TED) for processes currently used for P"+/N ultra-shallow junctions (USJ) fabrication. Indeed, the fundamental understanding of boron diffusion for low energy boron implantation is mandatory to evaluate the scalability of such processes for the coming complementary metal-oxide-semiconductor (CMOS) transistor generations. In these experiments, we characterize the boron anomalous diffusion, thanks to boron buried marker-layers obtained by epitaxial growth. B"+ and BF_2"+ ultra-low energy (ULE) implantations and plasma doping (PLAD) using BF_3 as precursor gas are carried out to compare the two techniques used for advanced USJ fabrication. Boron diffusion behaviors are analyzed via secondary ion mass spectrometry for annealing at 700 deg. C for 5 min and 15 min. Finally this paper brings some physical ...

Energy Technology Data Exchange (ETDEWEB)

Deformation in the overburden proves useful in deducing spatial and temporal changes in the volume of a producing reservoir. Based upon these changes we estimate diffusive travel times associated with the transient flow due to production, and then, as the solution of a linear inverse problem, the effective permeability of the reservoir. An advantage an approach based upon travel times, as opposed to one based upon the amplitude of surface deformation, is that it is much less sensitive to the exact geomechanical properties of the reservoir and overburden. Inequalities constrain the inversion, under the assumption that the fluid production only results in pore volume decreases within the reservoir. We apply the formulation to satellite-based estimates of deformation in the material overlying a thin gas production zone at the Krechba field in Algeria. The peak displacement after three years of gas production is approximately ...

Energy Technology Data Exchange (ETDEWEB)

Porous SnO{sub 2} nanotubes were prepared via electrospinning followed by calcination in air. As anode materials for lithium ion batteries, the porous nanotubes delivered a high discharge capacity of 807 mAh g{sup -1} after 50 cycles. Even after cycled at high rates, the electrode still retained a high fraction of its theoretical capacity. Such excellent performances of porous SnO{sub 2} nanotubes could be attributed to the porous and hollow structure which facilitated liquid electrolyte diffusion into the bulk materials and buffered large volume changes during lithium ions insertion/extraction. Furthermore, the nanoparticles of nanotubes provided the shorter diffusion length for lithium ions insertion which benefited in retaining the structural stability and good rate performance. Our results demonstrated that this simple method could be extended for the synthesis of porous metal oxide nanotubes with high performances in ...

Energy Technology Data Exchange (ETDEWEB)

A continuous gas laser may be operated reliably with an increased pressure level and current level without significant cathode sputtering. This increases the service life and the specific power of the laser. The design eliminates the formation of arcs in operational conditions, which also has a positive influence on laser operation. The proposed laser is used successfully in modern interferometry, in geodesy and in materials analysis. The laser design is characterized by the presence of separation rings inside the coaxial cathode. The separation rings are fastened to the anode. The anode is a perforated tube that is connected to two final protective rings. Electrodes from the housing pass through the final rings. In order to increase laser power, two or more lasers of such design are used and are positioned on the same axis in a single housing.

British Library Electronic Table of Contents (United Kingdom)

This work deals with a new route to modify polymer blend morphology in order to improve the porosity of gas diffusion layers (GDLs) for proton exchange membrane fuel cells (PEMFCs). First, electrically conductive polymer-based blends were carefully formulated using a twin-screw extrusion process. Blend electrical conductivity was ensured by the addition of high specific surface area carbon black and synthetic graphite flakes. Final GDL porosity, in particular its macroporosity, was generated by melt blending polyamide 11 (PA11) matrix with polystyrene (PS) followed by PS extraction with tetrahydrofuran (THF) solvent at room temperature. In order to improve GDL porosity by the optimisation of PS dispersion in the PA11 matrix, PA11/PS blends were compatibilised by the addition of 2 wt.-% of ...

British Library Electronic Table of Contents (United Kingdom)

Heat transfer through the gas diffusion layer (GDL) is a key process in the design and operation of a PEM fuel cell. The analysis of this process requires determination of the effective thermal conductivity as well as the thermal contact resistance associated with the interface between the GDL and adjacent surfaces/layers. In the present study, a custom-made test bed that allows the separation of effective thermal conductivity and thermal contact resistance in GDLs under vacuum and ambient conditions is described. Measurements under varying compressive loads are performed using Toray carbon paper samples with a porosity of 78% for a range of thicknesses. The measurements are complemented by compact analytical models that achieve good agreement with experimental data. A key finding is that ...

Energy Technology Data Exchange (ETDEWEB)

The diffusion of methane confined in nano-porous carbon aerogel with the average pore size 48 {angstrom} and porosity 60% was investigated as a function of pressure at T = 298 K using quasi-elastic neutron scattering (QENS). The diffusivity of methane shows a clear effect of confinement: it is about two orders of magnitude lower than in bulk at the same thermodynamic conditions and is close to the diffusivity of liquid methane at 100 K (i.e. {approx} 90 K below the liquid-gas critical temperature T{sub C} {approx} 191 K). The diffusion coefficient (D) of methane initially increases with pressure by a factor of {approx}2.5 from 3.47 {+-} 0.41 x 10{sup -10} m{sup 2} s{sup -1} at 0.482 MPa to D = 8.55 {+-} 0.33 x 10{sup -10} m{sup 2} s{sup -1} at 2.75 MPa and starts to decrease at higher pressures. An explanation of the observed non-monotonic behavior of the ...

Energy Technology Data Exchange (ETDEWEB)

A gas injection diesel engine was developed as an approaching measure to the diversification of fuel. Contrary to the usual low pressure gas application engine, this engine applies a so-called diffuse combustion method, in which high pressure (24.7Mpa) gas fuel is injected directly in the cylinder and is ignited and combusted by a little pilot fuel injected almost at the same time. The engine have following features. As a principle, it can attain the same heat efficiency and output rate as a diesel engine in any load range. It is excellent in responsibility to load fluctuation. There is no internal leakage of gas fuel to the scavenging chamber (the crank chamber) in the compression stroke. Not only a wide range of mixed combustion of gas fuel and heavy oil fuel, but also single combustion of heavy oil is possible. It is, therefore, drawing attention as an engine ...

Science.gov (United States)

The study is concerned with the Stefan problem of evaporation of a volatile component from its solution with a virtually non-volatile material. The analysis provides an analytical solution to the problem based on mass-transfer fundamentals. Results yield the evaporation rate, interfacial mole fractions, concentration profiles in the gas and liquid phases, and the location of the evaporation front. The analysis can be used to provide the binary liquid diffusion coefficient of the volatile component based on experimental data for the liquid gas interface position as a function of time. The requirements for such a measurement are discussed in terms of the volatility of the evaporating component and its initial concentration in the liquid mixture.[Figure not available: see fulltext.

International Nuclear Information System (INIS)

Production of ozone and OH radical is required to advance the plasma chemical reactions in the NOx removal processes for combustion gas treatment. The corona discharge to the water surface is expected to induce the good conditions for the proceeding of the NO oxidation and the NO_2 dissolution removal into water. In order to get the fundamental data of the corona discharge over the water surface, the positive and negative V-I characteristics and the ozone production were measured with the multi needle and the saw-edge type of the discharge electrodes. The pulse corona characteristics were also measured with some different waveforms of the applied pulse voltage. The experiments were carried out under the atmospheric pressure and room temperature. Both the DC and the pulse corona to the water surface showed a stable and almost the same V-I characteristics as to plate electrodes though the surface of water was waved by corona ...

International Nuclear Information System (INIS)

It has been reported by the present authors that behavior of tritium release from solid breeder grain is consisted of diffusion in grain, tritium transfer at surface layer and surface reactions on grain surface such as adsorption or isotope exchange reactions. Tritium release curves estimated using the tritium release model gave good agreement with observed tritium release curves from Li_4SiO_4, Li_2ZrO_3 or LiAlO_2. Tritium release behavior from Li_2TiO_3 under humid purge gas, dry purge gas and dry purge gas with hydrogen conditions is discussed in this study, tritium release curves using the release model that we proposed previously give a good agreements with experimental tritium release curves. Tritium effective diffusivity in the crystal grain of Li_2TiO_3 is also estimated in this study using a curve-fitting method applied to the release curves obtained under the humid purge ...

Energy Technology Data Exchange (ETDEWEB)

Objective of the project is characterization of electrode reactions in molten salt by using metal oxides and silica-based electrode. The scope of project are characterization of metal oxide properties in molten salt and miniaturization of 3-electrode electrochemical test cell. Electrochemical micro-cell for actinide-LiCl-KCl molten salt was newly designed. Electroless and electrochemical deposition technique was applied to Mo coating on quartz tube. From the design of electrode and 3-electrode electrochemical cell suitable for the tests in molten salt electrolyte, so it is anticipated to get the information on the electrochemical behavior of metallic electrode in molten salt and to secure the information on oxidation/reduction behavior of actinide

International Nuclear Information System (INIS)

Dynamical models are presented that start with interstellar gas in an initial diffuse state and consider their gravitational collapse and the formation of dense cores. Frozen-in tangled magnetic fields are included to mimic forces that might oppose gravitational contraction and whose effectiveness may increase with increasing core densities. Results suggest the possibility that dense cloud cores may be dynamically evolving ephemeral objects, such that their lifespan at a given core density decreases as that density increases. 66 refs.

Energy Technology Data Exchange (ETDEWEB)

The authors investigated the application of pulsed corona discharge process to the removal of SO{sub 2} and NO{sub x} from industrial flue gas of an ioron-ore sintering plant. This study was performed on a pilot scale, which is the most advanced demonstration of this process. The flow rate of 5000 m{sup 3}/h of the flue gas was successfully treated. The electrode structure of the corona reactor is the same with that of conventional electrostatic precipitator. The authors made use of magnetic pulse compression technology to produce repetitive high voltage pulse. Pulse width (full width at half maximum) was reduced to less than 1 {micro}s by connecting a resister in parallel with the corona reactor. An inductor was added to the resister in series to minimize the loss by restricting the current flowing through the resister. By this way, they were able to deliver pulse power with peak voltage of 110 kV and peak current of 2.3 ...

Energy Technology Data Exchange (ETDEWEB)

A mass transfer model has been developed to describe the rate of absorption (or desorption) of H{sub 2}S and CO{sub 2} in aqueous blends of a tertiary and a secondary or a primary amine. The model is based on penetration theory, and all significant chemical reactions are incorporated in the model. The reactions are taken to be reversible, with reactions involving only a proton transfer considered to be at equilibrium. The particular amines studied in this research were methyldiethanolamine (MDEA), a tertiary amine, and diethanolamine (DEA), a secondary amine. Key physicochemical data needed in the model, such as diffusion coefficients, kinetic rate constants, and gas solubilities, were measured. Experimental absorption rates of CO{sub 2} and H{sub 2}S were measured in a model gas-liquid contacting device and were compared with model predictions. Experiments were carried out for single amine solutions (both MDEA and DEA) and ...

Science.gov (United States)

A critical element of a retinal prosthesis is the stimulating electrode array, which is placed in close proximity to the retina. It is via this retinal-electrode interface that a retinal prosthesis electrically stimulates nerve cells to produce the perception of light. The impedance load seen by the current driver consists of the tissue resistance and the complex electrode impedance. The results in this paper show that the tissue resistance of the retina is significantly greater than that of the vitreous humor in the eye. Circuit models of the electrode-retina interface are used to parameterize the different contributors to the overall impedance.

Energy Technology Data Exchange (ETDEWEB)

Nitrogen has been added to stainless steels to improve mechanical strength and corrosion resistance. High nitrogen steel production is limited by high gas pressure requirements and low nitrogen solubility in the melt. One way to overcome this limitation is the addition of nitrogen in solid state because of its higher solubility in austenite. However, gas and salt bath nitriding have been done at temperatures around 550 C, where nitrogen solubility in the steel is still very low. High temperature nitriding has been, thus proposed to increase nitrogen contents in the steel but the presence of oxide layers on top of the steel is a barrier to nitrogen intake. In this paper a modified plasma nitriding process is proposed. The first step of this process is a hydrogen plasma sputtering for oxide removal, exposing active steel surface improving nitrogen pickup. This is followed by a nitriding step where high nitrogen contents are introduced in the ...

International Nuclear Information System (INIS)

During unit wise conditioning of unit 8, the vacuum started deteriorating inside the tube after a spark. The RGA reading was taken and it was found out that residual gas inside tube was sulphur hexafluoride. A leak was detected in second tube of unit number eight in between electrode 6 to 8. Leak was sealed with the sealant. Again leak check was done and no leak was found. The tank was closed and conditioning was started again. During the same unit number eight conditioning, leak developed again followed by a spark. So the damaged tube was replaced with a new accelerator tube. During the installation time the alignment of the machine was taken care. Again leak checking was done and the tube was baked properly. The tank was closed again and this particular unit was conditioned for about four days. The maximum voltage it has attained was 1.1 MV. (author)

International Nuclear Information System (INIS)

A series of cyclic voltammetry, chronoamperometry and electrochemical impedance experiments have been carried out in order to investigate the effect of cathode composition and porosity on the electrochemical characteristics of strontium-doped lanthanum, praseodymium and gadolinium cobaltite cathodes. The impedance responses at different electrode potentials of the half cell and symmetric single cell setups are compared and analyzed by the equivalent circuit modeling method. The deconvolution of impedance spectra for single cell cathode and anode reactions contributions based on the results of simultaneous analysis of half cells and symmetric single cells has been made by differential impedance real part vs. ac frequency plot analysis method. Noticeable influence of cathode chemical composition, meso-porosity and macro-porosity on the electrochemical activity of the oxygen electroreduction has been demonstrated. Seeming activation energy values have been calculated ...

Science.gov (United States)

The decomposition of three ?-lactam antibiotics (amoxicillin, oxacillin and ampicillin) in aqueous solution was investigated using a dielectric barrier discharge (DBD) in coaxial configuration. Solutions of concentration 100 mg/L were made to flow as a film over the surface of the inner electrode of the plasma reactor, so the discharge was generated at the gas-liquid interface. The electrical discharge was operated in pulsed regime, at room temperature and atmospheric pressure, in oxygen. Amoxicillin was degraded after 10 min plasma treatment, while the other two antibiotics required about 30 min for decomposition. The evolution of the degradation process was continuously followed using liquid chromatography-mass spectrometry (LC-MS), total organic carbon (TOC) and chemical oxygen demand (COD) analyses. PMID:21514950

Energy Technology Data Exchange (ETDEWEB)

This study has confirmed large seasonal and daily variations of Rn in soil gas, developed models for the effects of temperature and moisture on air-water Rn partition, inhibited Rn diffusion from wet soil into sparse large air-filled pores and effects of diffusion into bedrock, demonstrated that organic matter is a major host for 226Ra in soils and that organic-bound Ra largely determines the proportion of 222Rn emanated to pore space, shown that in contrast 220Rn is emanated mainly from 224Ra in Fe-oxides, detected significant disequilibrium between 226Ra and 238U in organic matter and in some recent glacial soils, demonstrated by computer models that air convection driven by temperature differences is expected in moderately permeable soils on hillsides.

Science.gov (United States)

A 65-yr-old female developed cough, fever and dyspnoea following repeated exposure to a home ultrasonic humidifier. High-resolution computed tomography showed ground-glass opacity in both lung fields. Arterial blood gas analysis gave an oxygen tension of 8.38 kPa (63 Torr). Pulmonary function testing revealed restrictive ventilatory impairment with a reduction in the diffusing capacity. The diagnosis of extrinsic allergic alveolitis (EAA) was confirmed by radiographic findings, pathological evidence of alveolitis and reproductive development by a provocation test to the humidifier water. The yeast Debaryomyces Hansenii was the only microorganism cultured from the water of the humidifier. The double diffusion precipitating test and lymphocyte proliferative response was positive for an extract of D. Hansenii, providing evidence to incriminate this fungus. This is the first described case of EAA caused by D. Hansenii. ...

British Library Electronic Table of Contents (United Kingdom)

This paper explores the through-/in-plane characteristics of water transport in the cathode gas diffusion layer (GDL) of a polymer electrolyte fuel cell (PEFC). Theoretical analysis is performed on the non-isothermal two-phase flow under flow channels. A dimensionless group Da (Damkohler number for PEFC operation), defined as the ratio of water generation rate to water vapor-phase removal rate, is formulated to characterize the flow regimes in a PEFC. This group, lumping geometrical parameters and physical properties, compares the water vapor-phase removal capability (via water diffusion and holding capacity) with the rate of water production by the oxygen reduction reaction. We find that this dimensionless group can be used to characterize the non-isothermal, two-phase phenomena: when Da&...

Energy Technology Data Exchange (ETDEWEB)

The absorption of carbonyl sulfide in aqueous methyldiethanolamine (MDEA) was studied over a range of temperatures and MDEA concentrations. MDEA is commonly used for selective absorption of hydrogen sulfide in the presence of carbon dioxide. However, sulfur in the form of COS may also be present and it is necessary that estimates of absorption rates of this compound be made. The objective of this study is to determine the physiochemical properties needed to predict COS absorption rates in aqueous MDEA. Free gas solubility and the diffusivity of COS in MDEA solutions were measured over the temperature range 15 to 40{sup 0}C for MDEA concentrations up to 30 weight per cent using the nitrous oxide analogy method. Solubilities were measured volumetrically in an equilibrium cell and diffusivities were measured using a laminar liquid jet absorber. The kinetics of the reaction between COS and MDEA were studied by measuring ...

Energy Technology Data Exchange (ETDEWEB)

The invention comprises an improved rechargeable zinc-air cell/battery having recirculating alkaline electrolyte and a zinc electrode comprising a porous foam support material which carries the active zinc electrode material. 5 figs.

British Library Electronic Table of Contents (United Kingdom)

Mesoporous V2O5/Nafion composite films have been used for the immobilization of tris(2,2prime-bipyridyl)ruthenium (II) (Ru(bpy)$\\rm{ {_{3}^{2+}}}$) on an electrode surface to yield a solid-state electrogenerated chemiluminescence (ECL) sensor. The electrochemical and ECL behavior of Ru(bpy)$\\rm{ {_{3}^{2+}}}$ ion-exchanged into the composite films has been characterized as a function of the amount of Nafion incorporated into the V2O5/Nafion composite. The composite film with 80% Nafion content has the largest pore diameter (4.19 nm) and yields the maximum ECL response for tripropylamine (TPA) because of the fast diffusion of analyte into the film with large pores. Due to the enlarged pore size and enhanced conductivity of the V2O5/Nafion composite, the present ECL sensor based on the compo...

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LiFePO{sub 4} cathode materials with distinct particle sizes were prepared by a planetary ball-milling method. The effects of particle size on the morphology, thermal stability and electrochemical performance of LiFePO{sub 4} cathode materials were investigated. The ball-milling method decreased particle size, thereby reducing the length of diffusion and improving the reversibility of the lithium ion intercalation/deintercalation. It is worth noting that the small particle sample prepared using malonic acid as a carbon source achieved a high capacity of 161 mAh g{sup -1} at a 0.1 C rate and had a very flat capacity curve during the early 50 cycles. However, the big particle samples ({proportional_to}400 nm) decayed more dramatically in capacity than the small particle size samples ({proportional_to}200 nm) at high current densities. The improvement in electrode performance was mainly due to the fine particles, the small size distribution, and ...

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Apparatus and methods for generating heat and electricity from the consumption of a variety of aluminum products comprise: (A) a reaction chamber containing an aqueous electrolyte solution and adapted for introduction therein of aluminum pieces of various shapes and sizes up to a certain maximum predetermined size and for effecting a chemical reaction between said aqueous electrolyte and said aluminum pieces yielding aluminum hydroxide and an intermediate reactant; (B) means for feeding said aluminum pieces into said reaction chamber in small quantities upon demand; (C) means for removing the heat generated in said chamber as a result of said reaction; (D) means for removing said aluminum hydroxide reaction product; and (E) means for oxidizing said intermediate reactant in an electrochemical cell, thereby generating electrical energy. The intermediate reactant is preferably hydrogen or zinc. The latter may be used in a slurry type zinc/air battery, whereas hydrogen is preferably ...

Energy Technology Data Exchange (ETDEWEB)

Six illitized samples from drillhole OL-KR12 in Olkiluoto were analyzed by helium gas methods for their diffusion coefficient, permeability and porosity. The diffusion coefficients measured varied in the range 2.1 x 10-10 - 3.5 x 10-8 m2/s, permeabilities in the range 6 x 10-21 - 5.8 x 10-16 m2, and porosities in the range 0.2 6.2%. Variations observed in these quantities were concluded to arise from the heterogeneous structure of the sample rock. A 4 mm x 4 mm x 4 mm subsample was sawed from each of the six samples for structural analysis by x-ray microtomography. The three-dimensional structure of tomographic reconstructions, and thereby that of the samples themselves, was analyzed visually, which confirmed their heterogeneity. Samples represent altered rock whose structure and thereby transport properties vary significantly depending on the local alteration history of the rock. (orig.)

Energy Technology Data Exchange (ETDEWEB)

This work deals with a new route to modify polymer blend morphology in order to improve the porosity of gas diffusion layers (GDLs) for proton exchange membrane fuel cells (PEMFCs). First, electrically conductive polymer-based blends were carefully formulated using a twin-screw extrusion process. Blend electrical conductivity was ensured by the addition of high specific surface area carbon black and synthetic graphite flakes. Final GDL porosity, in particular its macroporosity, was generated by melt blending polyamide 11 (PA11) matrix with polystyrene (PS) followed by PS extraction with tetrahydrofuran (THF) solvent at room temperature. In order to improve GDL porosity by the optimisation of PS dispersion in the PA11 matrix, PA11/PS blends were compatibilised by the addition of 2 wt.-% of clay. It was observed that both macroporosity and pore size distribution were beneficially modified after blend compatibilisation. Final GDL conductivity of ...

CERN Document Server

We present moderate resolution spectroscopy of extraplanar diffuse ionized gas (EDIG) emission in the edge-on spiral galaxy NGC 4302. The spectra were obtained with the SparsePak integral field unit (IFU) at the WIYN Observatory. The spectra are used to construct position-velocity (PV) diagrams at several ranges of heights above the midplane. Azimuthal velocities are directly extracted from the PV diagrams using the envelope tracing method, and indicate an extremely steep dropoff in rotational velocity with increasing height, with magnitude ~30 km/s/kpc. We find evidence for a radial variation in the velocity gradient on the receding side. We have also performed artificial observations of galaxy models in an attempt to match the PV diagrams. The results of a statistical analysis also favor a gradient of ~30 km/s/kpc. We compare these results with an entirely ballistic model of disk-halo flow, and find a strong dichotomy between the observed ...

Energy Technology Data Exchange (ETDEWEB)

Heat transfer through the gas diffusion layer (GDL) is a key process in the design and operation of a PEM fuel cell. The analysis of this process requires determination of the effective thermal conductivity as well as the thermal contact resistance associated with the interface between the GDL and adjacent surfaces/layers. In the present study, a custom-made test bed that allows the separation of effective thermal conductivity and thermal contact resistance in GDLs under vacuum and ambient conditions is described. Measurements under varying compressive loads are performed using Toray carbon paper samples with a porosity of 78% for a range of thicknesses. The measurements are complemented by compact analytical models that achieve good agreement with experimental data. A key finding is that thermal contact resistance is the dominant component of the total thermal resistance; neglecting this phenomenon may result in significant errors in ...

Energy Technology Data Exchange (ETDEWEB)

In situ Auger sputter depth profiles of saturation implants of 3 keV N/sub 2//sup +/ in silicon at room temperature exhibit a sharp peak in the nitrogen concentration in the outermost layers, followed by a monotonic decrease. No broad plateau was observed. The energy of the Auger line corresponding to the Si(2p) core electron excitation, monitored throughout the profiling, exhibits a chemical shift of up to 7 eV at the surface peak concentration. Inert gas ion post-bombardment of unsaturated implants significantly modifies the profile, and supports the suggestion that the surface peak arises through radiation enhanced diffusion of implanted atoms.

International Nuclear Information System (INIS)

The objective of this paper is to present a theoretical evaluation of soil and house related factors that may affect the transport of radon from the soil into houses. A two-dimensional mathematical model was used to simulate the diffusive and convective transport of radon into the house through idealized openings in the understructure. With the help of model predictions we tried to find out whether diffusion or convection predominates and under which circumstances. Radon transport through cracks in the house understructure is influenced mainly by the soil permeability, radon concentration at the soil-crack interface, the total area of cracks and the pressure difference across cracks. Because of its large range of variability, the soil permeability appears to have the greatest effect on the radon transport through cracks. At permeabilities below 1x10"-"1"2 m"2 diffusive transport predominates and is almost invariable with ...

Energy Technology Data Exchange (ETDEWEB)

This study was the analyse the relationship between properties of ion nitrided Fe sintered material and parameters of plasma nitriding process. Pure fe sintered materials (relative density : 92%) were fabricated by hot-pressing and nitrided under pulsed DC plasma for 4 hours. The large number of parameters in plasma diffusion treatment allows close control of the process so that surface layers with defined microstructures and properties can be obtained. The number of micropores in nitriding layer can be reduced in pulsed DC plasma by reducing the plasma power and by varying the gas mixture. The phase constitution of compound layer of nitrided Fe sintered material were influenced by gas mixture (N{sub 2} : H{sub 2}) and pulsed ratio (pulse on/off time ratio)

Energy Technology Data Exchange (ETDEWEB)

To clarify the mechanism of plasma nitriding, the authors examined the optical microstructure, the hardness, the precipitation, and the concentration of dissolved nitrogen in Fe-18Cr-9Ni nitrided using plasma in the range of 723-823 K. Compared with ammonia-gas nitriding, the features of plasma nitriding are the formation of small chromium-nitride precipitates (CrN), the absence of an externally nitrided layer, the high concentration of dissolved nitrogen, and the high hardness (HV = 1,200). The diffusion coefficient of nitrogen in the present alloy was determined using the growth rate of the internally nitrided layer, based on calculations used in internal oxidation. Plasma- and gas-nitriding were also compared with respect to the growth rate of the nitrided layer.

Energy Technology Data Exchange (ETDEWEB)

Flame lengths inside circular tubes, using an (in-shot) atmospheric burner design commonly found in gas-fired residential furnaces were visually observed for natural gas and air under various operating conditions. The flame length data were reduced into dimensionless flame lengths, which were shown to be linearly proportional to the Peclet number of the fuel and air mixture. The dimensionless flame length dependence reported does not scale according to the classical flame models: pre-mixed (laminar) flame or diffusion flame. Instead, the flame length dependence was found to scale with the fuel burn speed, gas/mixture properties (evaluated at the adiabatic flame temperature), and flow parameters. Currently, this is the only flame length study available for the standard atmospheric burner designs commonly used in residential heating products. The results and data reduction provide an easy method to ...

International Nuclear Information System (INIS)

The trifluoroacetate metal-organic decomposition route to YBa_2Cu_3O_7 film growth was investigated in order to bring new insights in the growth mechanism and its dependence on processing conditions and critical current density. Precursor films were processed on LaAlO_3 substrates at different total pressure, oxygen partial pressure, water vapor partial pressure, and volume gas flow rate keeping the growth temperature at 740 "0C. The influence of these various experimental parameters on the film growth rate, which was evaluated by in situ electrical resistance measurements, was studied thoroughly. It was found that the growth rate is nearly independent of the oxygen pressure and proportional to the square root of the water pressure. Additionally, the growth rate increases with a decrease of the total pressure or an increase of the gas flow rate. An empirical multi-exponential model simulates the experimental data, however, a better ...

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Energy Technology Data Exchange (ETDEWEB)

Singlet oxygen generators are multiphase flow chemical reactors used to generate energetic oxygen to be used as a fuel for chemical oxygen iodine lasers. In this paper, a theoretical model of the generator is presented along with its solutions over ranges of parameter space and oxygen maximizing optimizations. The singlet oxygen generator (SOG) is a low-pressure, multiphase flow chemical reactor that is used to produce molecular oxygen in an electronically excited state, i.e. singlet delta oxygen. The primary product of the reactor, the energetic oxygen, is used in a stage immediately succeeding the SOG to dissociate and energize iodine. The gas mixture including the iodine is accelerated to a supersonic speed and lased. Thus the SOG is the fuel generator for the chemical oxygen iodine laser (COIL). The COIL has important application for both military purposes--it was developed by the US Air Force in the 1970s--and, as the infrared beam is readily absorbed by ...

Energy Technology Data Exchange (ETDEWEB)

The present invention concerns a negative ion source electrode which can be preferably used in a neutral particle injection device using negative ions for a thermonuclear reactor. Negative ion beams are deflected to the direction opposite to the deflecting direction by magnetic fields by using an electron suppression electrode having electrode holes with the position previously displaced before negative ion beams are accelerated to have a high energy by an accelerator thereby correcting the orbit of the negative ion beams easily. In addition, since the deflection correction electrode having the electrode holes is disposed, a proper voltage is applied to the deflection correction electrode to correct the orbit of the negative ion beams conveniently. Since the deflection correction electrode has a simple structure of a thin flat plate having ...

Energy Technology Data Exchange (ETDEWEB)

The key component for improving the energy efficiency and cycle life of the electrically rechargeable zinc-air battery is the bifunctional air electrode. The air electrodes described in this paper contained different types of carbon black as the substrate for the perovskite catalyst (La{sub 0.6}Ca{sub 0.4}CoO{sub 3}). Morphological and physical properties of the carbon substrates play an important role in enhancing the activity and stability of the bifunctional air electrode. Current-potential curves and cycle-life tests were applied in order to gather information on the activity and stability of these electrodes. (authors)

Science.gov (United States)

In this study, different proportions of silver-palladium alloy used as an inner electrode are adopted to fabricate (Zn,Mg)TiO3-based multilayer ceramic capacitors. Effects of sintering temperature, and measuring frequency on the dielectric properties of the samples with different proportions of the Pd-Ag inner electrode are investigated. The continuity of the inner electrode and the proportion of Pd-Ag of the inner electrode of samples sintered at different temperatures play important roles in determining the dielectric properties.

Energy Technology Data Exchange (ETDEWEB)

A method is described of controlling an anodic protection system in a heat exchanger comprising: (a) installing at least one cathode within the heat exchanger, at least one cathode being aligned with the longitudinal axis of the heat exchanger and extending substantially along the length of the heat exchanger; (b) installing a first reference electrode within and at one end of the heat exchanger, the first reference electrode having a first controller having a set point for control and a power supply having an output creating an electrical potential between at least one cathode and the heat exchanger; (c) measuring the electrical potential of the heat exchanger with the first reference electrode; (d) operating the first controller in response to measurements made by the first reference electrode to change the output of the power supply; (e) installing a second reference electrode ...

International Nuclear Information System (INIS)

Constant pull rate tests were conducted on tensile specimens of Inconel Alloy 600, Incoloy Alloy 800, and Type 304 stainless steel in deaerated 10% NaOH solution at 288 C (550 F) with a cover gas of 5% H_2 in N_2. The pull rate used for most experiments was 3.3 x 10"-"6 cm/s, which corresponds to an initial strain rate of 3 x 10"-"6 s"-"1. The electrical potential of the specimens was controlled by a potentiostat using a nickel wire as a hydrogen reference electrode. Under open circuit conditions, Type 304 stainless steel specimens cracked rapidly, but Alloys 600 and 800 specimens exhibited only ductile fracture. However, cracks readily formed in Alloy 800 specimens at potentials in the +50 to +300 mV range and in Alloy 600 specimens at potentials in the +150 to +250 mV range. Scanning electron microscope (SEM) photographs of some of the cracked specimen surfaces showed the transition from ductile to brittle fracture as a consequence of changes ...

Energy Technology Data Exchange (ETDEWEB)

In the 80's, because of the oil crisis, the Natural Gas (NG) appeared as a fuel with a great potential for Diesel replacement in Heavy Duty Vehicles. At that time, PETROBRAS with other companies have developed partial conversion technologies from Diesel to NG, known as 'Dual Fuel'. Engine dynamometer and vehicle bus tests have been developed to verify its technical and economical viability. Because of several factors, the Dual Fuel Program did not advance and the experience was interrupted. At the same time, other experiences using NG Otto Cycle bus engines, manufactured in Brazil, have been conducted, mainly at Sao Paulo, nevertheless, without expansion. Currently, factors as increase of the NG converted light vehicles fleet; the NG excess in the National Market, which has contributed to the NG distribution net expansion; the Environmental Legislature in vigor, that continuously determine lower emission limits; the government interest in ...

Energy Technology Data Exchange (ETDEWEB)

This report introduces a microprocessor system composed of a Z-80 single-board computer controlling a gas-carburizing process. The system has 7 analogical input and output signals 24 switch signal-input and 12 switch signal-output signals, which are applicable for temperature, carbon potential, and mechanical-movement control of multipurpose sealed furnaces, or for mutiple-zone temperature, carbon potential, and mechanical-movement control of continuous gas carburizing furnaces; or for distributed control of pit-type carburizing furnaces. The setpoints of variables, such as treating time, temperature, carbon potential of carburizing period, carbon potential of diffusion period, depth of carburizing layer, P.I.D. etc., are entered by keyboard and stored into memories, and actual values are displayed by digital tubes. Furthermore, the fault of thermocouple, oxygen probe, or infrared CO/sub 2/ analyzer; carbon potential, or ...

Science.gov (United States)

In the course of observing by means of Auger spectroscopy graphite gasification reactions catalyzed by metals, it has been found that in the presence of hydrogen, nickel appears to diffuse from the surface into the bulk of the graphite. When potassium is deposited on graphite, it is volatilized above 400/sup 0/C. Surprisingly the production of methane and carbon dioxide from the reaction of graphite and steam was catalyzed by potassium at as low a temperature as 250/sup 0/C. It has been shown that literature on the alkylation of benzene with synthesis gas is erroneous and that the products reported are due to Lewis acid catalyzed cracking of benzene. A novel cobalt mediated, reversible cleavage of a vinyl-hydrogen bond has been discovered. All products from the thermal decomposition of tetralin have been identified. The stereochemistry of cis-1, 2 dihydrotetralin was determined. In the utilization of the water gas shift ...

International Nuclear Information System (INIS)

Corona discharge has been investigated for the treatment of off-gases arising from nuclear fuel reprocessing operations, in particular Dissolver off-Gases (DOG). Results are presented of studies carried out on single tube, wire-in-tube experimental rigs to examine the behaviour of molecular iodine, organic iodine and oxides of nitrogen (NOx). The effect of corona current, gas residence time, electrode configuration, oxygen concentration and moisture content are discussed. Decontamination Factors (DF's) of greater than 104 (> 99.99% removal) have been achieved for both molecular and organic iodine. Efficient NOx removal has also been demonstrated. Moisture and NOx both interfere with iodine removal above certain concentrations. To overcome this a two stage corona system has been developed consisting of a primary continuously irrigated corona unit followed by a dehumidifier prior to a secondary dry corona unit.

Energy Technology Data Exchange (ETDEWEB)

Commercially available melter technologies were tested during 1994-95 as part of a multiphase program to test candidate technologies for vitrification of the low-level waste (LLW) stream to be derived from retrieval and pretreatment of Hanford Site tank wastes. Seven vendors were selected for Phase 1 testing to demonstrate vitrification of a high sodium content liquid LLW simulant. The tested melter technologies included four Joule-heated melters, a carbon electrode melter, a combustion melter, and a plasma melter. Various dry and slurry melter feed preparation processes were also tested. Various feed material samples, product glass samples, and process offgas streams were characterized to provide data for evaluation of process decontamination factors and material mass balances for each vitrification technology. This report describes the melter mass balance evaluations and results for six of the Phase 1 LLW melter vendor demonstration tests.

Energy Technology Data Exchange (ETDEWEB)

Because the number of neutrons and gamma rays and the energy spectrum of particles from spontaneous fission are well characterized for {sup 252}Cf, it can be used as a timed source of fission neutrons and gamma rays. The first such usage incorporated a {sup 252}Cf source into gas scintillators. This paper describes a timed source of neutrons and gamma rays made by depositing {sup 252}Cf on one electrode of a parallel plate ionization chamber that can then be used for determining detection-system characteristics. The emission time of neutrons from spontaneous fission has also been determined by recording the emission time of prompt gamma rays from a {sup 252}Cf source (not incorporated into a detector) adjacent to the surface of a solid or liquid scintillator. This well characterized source of neutrons can thus be used as a randomly pulsed source for a variety of applications. This paper illustrates the use of this type of source to determine ...

UK PubMed Central (United Kingdom)

Diffusion in the extracellular space (ECS) of the brain is constrained by the volume fraction and the tortuosity and a modified diffusion equation represents the transport behavior of many molecules...Full Text Available

CERN Document Server

The Westerbork Northern Sky Survey (WENSS) and the NRAO/VLA Sky Survey (NVSS) were used to determine an upper limit to the diffuse radio flux from the nearby cluster Abell 2199. For the entire cluster, this limit is <3.25 Jy at 327 MHz from WENSS; for the inner 15' radius, the limit is <168 mJy at 1.4 GHz. These limits are used to constrain the cluster magnetic field by requiring that the radio flux be consistent with the hard X-ray (HXR) flux observed by BeppoSAX, assuming that the observed HXR excess is due to inverse Compton (IC) scattering of cosmic microwave background photons by relativistic electrons in the intracluster gas. We find that the magnetic field must be very weak (<0.073 uG) in order to avoid producing an observable radio halo. We also consider the possibility that the HXR excess is due to nonthermal bremsstrahlung (NTB) by a population of suprathermal electrons which are being accelerated to higher energies. We find ...

Science.gov (United States)

The relationship between processing, microstructure, and properties was studied for A-15 compounds in multifilamentary composites produced by solid-state diffusion and in thin-film samples produced by vapor deposition. Grain sizes of A-15 superconducting compounds were measured by transmission electron microscopy of multifilamentary composites reacted at various temperatures. Critical current densities at 4.2 K and fields up to 6 T were found to be similar for niobium-tin, vanadium-gallium, and vanadium-silicon of the same grain size. Study of the Cu-V-Si phase diagram led to the production of improved multifilamentary vanadium-silicon conductors. The effects of various alloying elements on A-15 layers produced by solid-state diffusion were studied. The most promising new observation was that tantalum can be incorporated into niobium-tin reaction layers, leading to an enhancement of critical currents at high fields. The critical temperature of ...

International Nuclear Information System (INIS)

Low pressure silane plasmas are known for their ability to synthesize silicon nanoparticles via gas phase nucleation. While in the past this particle formation has often been considered from the viewpoint of a contamination problem in semiconductor processing, we here describe a silane low pressure plasma that enables the synthesis of highly oriented, cubic-shaped silicon nanocrystals with a rather monodisperse size distribution. These silicon nanocubes have successfully been used in the manufacture of single nanoparticle vertical transistors. We discuss the advantages of this new paradigm of building nanoelectronic devices. The plasma synthesis process is characterized in more detail than in prior work. The particle nucleation, growth and shape evolution are studied. Results indicate that the process provides two spatially distinct zones: a diffuse plasma for particle growth and a constricted plasma zone for particle annealing. Measurements of ...

Energy Technology Data Exchange (ETDEWEB)

This report for the Swiss Federal Office of Energy (SFOE) presents the overview reports made by SFOE Heads of Program on work done in 2007. Projects reported on in the natural gas-fired fuel cell area include the EU-project REAL-SFOC, the long-term testing of anode-supported SOFC stacks, intermediate-temperature fuel cells based on proton conducting electrolytes, the interdisciplinary ONEBAT project and lifetime-enhancement of SOFC stacks for CHP applications. In the polymer-electrolyte fuel cell (PEFC) area, projects concerning proton-conducting polymer membranes, factors limiting the lifetime of fuel cell membranes, a new highly active oxygen reduction electrode for PEM fuel cell and zinc/air battery applications, the enhancement of PEFC durability and reliability, model-based investigation of PEFC performance, and local gas analysis of PE fuel cells are briefly reported on. Long-term research activities in the hydrogen ...

UK PubMed Central (United Kingdom)

Purpose.Since 2002, six blind patients have undergone implantation of an epiretinal 4 × 4 electrode array designed to directly stimulate the remaining cells of the retina...Full Text Available

International Nuclear Information System (INIS)

In this paper, results on ozone production by atmospheric pulsed discharge, are reported. In the research, two types of ozonizer (Type I and Type II) have been used to investigate improvements of ozone concentration and production efficiency. The ozonizer has plane-to-plane metal electrodes structure, and pre-ionization electrodes are placed on the high voltage electrodes (Type I). In Type II, the surface of grounded electrode with 20 mm of width is covered partly by dielectric (thin rubber) with 11 mm of width, while the geometry of both metal electrodes is same to Type I. In the case of Type I, maximum concentration of about 100 ppm and maximum yield of 70 g/kWh were obtained at input power of 0.3 W. On the other hands, in the case of Type II, 800 ppm and 100 g/kWh were obtained at input power of 1.5 W. It was found that the ozone concentration and production yield were improved ...

UK PubMed Central (United Kingdom)

We present an algorithm to identify individual neural spikes observed on high-density multi-electrode arrays (MEAs). Our method can distinguish large numbers of distinct neural units, even when spikes...Full Text Available

Energy Technology Data Exchange (ETDEWEB)

This paper describes a new idea for zinc-air battery design. The novel idea is a porous zinc electrode surrounded with a supersaturated zincate solution. 3 figs. (JDH)

International Science & Technology Center (ISTC)

Development of Bipolar Separator Plates with Porous Insertions of Metal Felt as Bearing Surfaces for Fuel Cell Electrodes

Energy Technology Data Exchange (ETDEWEB)

For the development of a long-lived electrically rechargeable zinc/air battery, the structure and wettability of pasted zinc electrodes were optimized. Pasted zinc electrodes, having the same nominal capacities but containing 1% to 10% cellulose, were prepared and tested under defined charge and discharge conditions in zinc-oxygen cells. The maximum power as well as the cycle life of these cells were measured. After different times of operation, the porosity and the pore size distribution of the pasted zinc electrodes were measured by means of mercury porosimetry. (author) 4 figs., 1 tab., 6 refs.

Energy Technology Data Exchange (ETDEWEB)

This paper presents a numerical study on the formation history of coalbed methane (CBM) reservoir in the southeast edge of Ordos Basin, China. The coal seams studied belong to the Late Palaeozoic coal-bearing series. These coal seams have a burial history and experienced the process of subsidence, rapid subsidence alternated with uplift and then uplift, sequentially, and underwent the geothermal actions at normal, extremely high, and then normal temperatures, respectively. Coal organic matter of the coal seams matured in the Triassic Period and in the Late Jurassic to Early Cretaceous Period. The results from numerical simulation reveal that CBM reservoir evolution history can be classified into five stages, namely primary, initial, stagnant, active and dissipative stages. In the first (primary) stage, coal rank was very low and there was little methane generated and stored in the coal seams. In the second (initial) stage, the coal was converted to middle-high volatile bituminous coal. ...

Energy Technology Data Exchange (ETDEWEB)

The technique of air diffusion by shifting presents several advantages in terms of thermal comfort, indoor air quality and energy conservation. This book presents the principle, dimensioning, and implementation of air shifting diffusion systems. (J.S.)

British Library Electronic Table of Contents (United Kingdom)

The transport of liquid water and gaseous reactants through a gas diffusion layer (GDL) is one of the most important water management issues in a proton exchange membrane fuel cell (PEMFC). In this work, the liquid water breakthrough dynamics, characterized by the capillary pressure and water saturation, across GDLs with and without a microporous layer (MPL) are studied in an ex-situ setup which closely simulates a real fuel cell configuration and operating conditions. The results reveal that recurrent breakthroughs are observed for all of the GDL samples tested, indicating the presence of an intermittent water drainage mechanism in the GDL. This is accounted for by the breakdown and redevelopment of the continuous water paths during water drainage as demonstrated by Haines jumps. For GDL ...

International Nuclear Information System (INIS)

In the present investigation, the properties of plasma nitrided AISI 304 steel were studied by changing the presence of nitrogen in the gas mixture. The plasma nitriding was performed at temperature -560 deg C, pressure -4 mbar and duration 24 hours. The nitrided samples were characterized by evaluating the phase composition, micro hardness, and diffusion layer thickness. The phase analysis indicates the mixed phases of CrN and Fe_3N, Fe_3N and Fe_4N which has the highest intensity. The results show the glow discharge plasma nitriding in presence of N_2 (80 vol. %) and H_2 (rest) produced higher hardness as well as higher case depth. (author)

International Nuclear Information System (INIS)

The authors describe a new method which makes it possible to determine the radial distribution of the diffuse component of galactic gamma rays outside the solar circle. They use the observation that a good correlation exists between gamma-ray intensities and total column densities of the local interstellar gas and that the fractional column density of H_2<0.1 HI outside the solar circle. Thus the gamma-ray intensities are shown to be proportional to N(HI). The authors use the kinematics of the HI to determine the distances from which various fractions of the emission originate in the second and third galactic quadrants. Preliminary results of our analysis show that a significant flux of gamma rays originates from distances as large as 18 kpc from the galactic centre. (Auth.).

Energy Technology Data Exchange (ETDEWEB)

The influence of plasma nitriding on the fatigue behaviour of AISI 4140 low-alloy steel was investigated under varying process conditions of temperature (500-600 C), time (1-12 h), heat treatment before ion nitriding (quenched and tempered, normalized) and gas mixture (50% H{sub 2}-50% N{sub 2}). A rotating bending fatigue machine was used to determine the fatigue strength. It was found that the plasma nitriding improves the fatigue strength and increases the fatigue limit depending on the surface hardness of the case depth. The microstructure of surface and diffusion layers was examined by optical microscopy. The fracture surface of specimens and the origin of fatigue cracks were observed by scanning electron microscopy.

Energy Technology Data Exchange (ETDEWEB)

Papers are presented on the modeling, dispersion, formation, transformation, monitoring and biological effects of atmospheric pollution. Specific topics include a prognostic mesoscale model for pollutant transport and diffusion, commuter exposure modeling, a Gaussian plume model for an urban area, carbon monoxide dispersion in an urbanized area, wind-tunnel modeling of flue gas dispersion, the regional-scale transport of fine aerosol components in eastern North America, and a Markov process for the generation of hourly average wind vectors. Attention is also given to photochemical aerosol formation in multicomponent systems, heterogeneous nitrogen oxide-particulate reactions, the generation and measurement of primary soot aerosols of size between 50 and 400 A, inertial particle size classification techniques, the design of air quality monitoring networks, visibilities in polluted and unpolluted areas, and monitoring air quality according to an ...

Energy Technology Data Exchange (ETDEWEB)

This patent describes an improved zinc electrode for a rechargeable zinc-air battery comprising an outer frame and a porous foam electrode support within the frame which is treated prior to the deposition of zinc thereon to inhibit the formation of zinc dendrites on the external surface thereof. The outer frame is provided with passageways for circulating an alkaline electrolyte through the treated zinc-coated porous foam. A novel rechargeable zinc-air battery system is also disclosed.

International Nuclear Information System (INIS)

The aim of the work in this thesis is to investigate the convective and diffusive transport in the TM chemistry transport model, and to investigate some aspects of the consequences for NOx. The large inaccuracy and uncertainty in the description of processes like convection and turbulent diffusion, the strong dependence of the radiative forcing of ozone on its vertical distribution, and the strong dependence of the ozone production on the distribution of NOx, are the main motivation. The availability of the ERA-40 data, where convective data and vertical diffusion coefficients are archived, allows a study of the effect of different convective mass flux sets, and different vertical diffusion coefficients on the model-simulated distribution of tracers. In this thesis the following questions are addressed : (1) How large is the sensitivity of the (model simulated) distribution of ozone and nitrogen oxides ...

International Science & Technology Center (ISTC)

Research on Diffusion Zinc Cladding of Structural Steels, as Well as Their Mechanical and Corrosion Properties to Replace Their Cyanic Cadmium Plating

CERN Document Server

Recent high spatial and spectral resolution investigations of the diffuse interstellar medium (ISM) have found significant evidence for small-scale variations in the interstellar gas on scales less than or equal to 1 pc. To better understand the nature of small-scale variations in the ISM, we have used the KPNO WIYN Hydra multi-object spectrograph, which has a mapping advantage over the single-axis, single-scale limitations of studies using high proper motion stars and binary stars, to obtain moderate resolution (~12 km/s) interstellar Na I D absorption spectra of 172 stars toward the double open cluster h and Chi Persei. All of the sightlines toward the 150 stars with spectra that reveal absorption from the Perseus spiral arm show different interstellar Na I D absorption profiles in the Perseus arm gas. Additionally, we have utilized the KPNO Coude Feed spectrograph to obtain high-resolution (~3 km/s) interstellar Na I D ...

Energy Technology Data Exchange (ETDEWEB)

Sputter-deposited tantalum (Ta) and reactively sputter-deposited Ta-nitride films were studied with respect to the passivation capability against copper (Cu) oxidation in thermal O{sub 2} ambient. A 200 {angstrom} Ta or Ta-nitride film was sputter-deposited on a 2,000 {angstrom} Cu film using a Ta target in an Ar/N{sub 2} gas mixture. With Ta passivation, Cu was not oxidized at temperatures up to 400 C, which can be further improved by using passivation of an amorphous Ta-nitride film deposited in an appropriate condition. The absence of long-range defects in the Ta-nitride film was presumably responsible for this improvement. However, sputtering-induced surface damage by excess N{sub 2} in the sputter gas mixture may reduce the passivation capability of Ta-nitride films. When the passivated Cu was oxidized, the Cu oxides always resided in the top surface region. That is, in the oxidation process, Cu diffused through the ...

Energy Technology Data Exchange (ETDEWEB)

The two-phase annular regime is characterized by a high velocity gas stream flowing through the core of the tube surrounded by a thin, highly agitated liquid film flowing concurrently along the tube wall. Part of the liquid may be entrained as droplets in the gas phase. The specific goals of this study were to measure fully developed rates of interchange and entrained fraction over a wide range of flow variables in the upward configuration of the annular regime, to obtain a more fundamental understanding of liquid interchange phenomena via studies of liquid film characteristics and to develop an improved design correlation for the entrained fraction. Towards this end, air-water experiments were conducted in two vertical pipe lines, 2.54 and 4.20 cm in diameter. Air velocities ranging from 20 to 120 m/s and total liquid flow rates ranging from 10 to 100 g/s were investigated. Two models for the rate of atomization, proposed by Tatterson (1975) ...

Energy Technology Data Exchange (ETDEWEB)

A focused ion beam (FIB) system produces a final beam spot size down to 0.1 .mu.m or less and an ion beam output current on the order of microamps. The FIB system increases ion source brightness by properly configuring the first (plasma) and second (extraction) electrodes. The first electrode is configured to have a high aperture diameter to electrode thickness aspect ratio. Additional accelerator and focusing electrodes are used to produce the final beam. As few as five electrodes can be used, providing a very compact FIB system with a length down to only 20 mm. Multibeamlet arrangements with a single ion source can be produced to increase throughput. The FIB system can be used for nanolithography and doping applications for fabrication of semiconductor devices with minimum feature sizes of 0.1 .mu.m or less.

Energy Technology Data Exchange (ETDEWEB)

Ultrafine particles of Co-P were synthesized by direct ball milling of Co and P powders and also investigated as a reversible hydrogen storage electrode material. The electrochemical results demonstrated that the reversible charge-discharge capacity of the Co-P electrode can reach more than 300mAh/g. In addition, the cycling ability and high rate capability of the Co-P electrode are excellent with only 5% capacity decay after 100 cycles at a high rate of 300mA/g. The temperature-programmed desorption measurements (TPD) of the Co-P electrode revealed that the charge and discharge reactions of the Co-P electrode proceeds predominantly through electrochemical hydrogen storage mechanism and the electrooxidation of cobalt contributes only a negligible part to the reversible electrochemical capacity. (author)

Energy Technology Data Exchange (ETDEWEB)

Radon migration in porous, earthen materials is characterized by diffusion in both the air and water components of the system as well as by the interaction of the radon between the air and water. The size distribution and configuration of the pore spaces and their moisture distributions are key parameters in determining the radon diffusion coefficient for the bulk material. A mathematical model is developed and presented for calculating radon diffusion coefficients solely from the moisture content and pore size distribution of a soil, reducing the need for resorting to radon diffusion measurements. The resulting diffusion coefficients increase with the median pore diameter of the soil and decrease with increasing widths of the pore size distribution. The calculated diffusion coefficients are suitable for use in simple homogeneous-medium ...

Energy Technology Data Exchange (ETDEWEB)

This report summarizes the results of research conducted during the sixteen month continuation of a program to develop rechargeable zinc-air batteries for electric vehicles. The zinc-air technology under development incorporates a metal foam substrate for the zinc electrode, with flow of electrolyte through the foam during battery operation. In this soluble'' zinc electrode the zincate discharge product dissolves completely in the electrolyte stream. Cycle testing at Lawrence Berkeley Laboratory, where the electrode was invented, and at MATSI showed that this approach avoids the zinc electrode shape change phenomenon. Further, electrolyte flow has been shown to be necessary to achieve significant cycle life (> 25 cycles) in this open system. Without it, water loss through the oxygen electrode results in high-resistance failure of the cell. The Phase I program, ...

Energy Technology Data Exchange (ETDEWEB)

The surface enhanced Raman scattering (SERS) spectra of piperidine in silver colloid solution, on roughened silver electrode and on roughened silver electrode modified with silver nanoparticles were studied, and the high-quality SERS spectra of piperidine on roughened silver electrode modified with silver nanoparticles were obtained for the first time. Surface selection rules derived from the EM enhancement model were employed to deduce piperidine orientations on the different surfaces. On the basis of this, two models of piperidine adsorbed on the surface of the silver nanoparticles were built, and DFT-B3PW91/LanL2dz was applied to calculate the Raman frequencies. It proves that, at higher potential values, the piperidine is perpendicularly standing on the roughened silver electrode surface though its lone-electron pair, but in silver colloid solution and on the silver nanoparticles modified silver ...

Energy Technology Data Exchange (ETDEWEB)

This patent describes an energy storage device. It comprises: a working electrode, a counter electrode, electrically isolated from the working electrode; an electrolyte in contact with the working electrode and the counter electrode, and means for collecting electrical current therefrom; the working electrode consisting essentially of an amorphous metal alloy of the formula: A{sub {ital a}}M{sub {ital b}}M{prime}{sub {ital c}}, wherein A is at least one metal selected from the group consisting of Ag, Hg and Pt; M is at least one metal selected from the group consisting of Pb, Cu, Cr, Mo, W, Ni, Al, Co, Fe, Zn, Ru, Cd and Mn; M{prime} is at lest one of the elements selected from the group consisting of Ca, Mg, Ti, Zr, Hf, V, Nb and Ta; and wherein a ranges from about 0.005 to about 0.80; b ranges from 0.05 to about 0.70; and c ranges from about 0.08 to about ...

Energy Technology Data Exchange (ETDEWEB)

A small-sized inexpensive carbon dioxide gassensor was prepared using LiTi2 (PO4)3 +0.2Li3PO4 as lithium-ion conductive, solid electrolyte and its detectability and the effects of co-existing gases were examined. The above compound was obtained by the method where a powdery mixture of Li2CO3, TiO2, (NH4)H2PO4 and Li3PO3 was molded in the presence of a sintering assistant, subjected to hydrostatic press, and sintered. Measurements were made on the relation between CO2 concentration and the electromotive force of the CO2 sensor made of the compound and the influence of concentration of coexisting NO2, SO2 or CH4 on the electromotive force. The results are summarized as follows. A linear relation exists between the electromotive force and the CO2 concentration in the range from 80ppm to 1% to show a good agreement between theoretical and experimental results. Coexistence of NO2 the range of 100-4500ppm has no influence on the electromotive force. Coexistence of methane gives a linear ...

Energy Technology Data Exchange (ETDEWEB)

The permeation of hydrogen through steam generator tubes at high temperatures ({approx} 300 degrees C) has been studied using an electrochemical technique. With this technique, hydrogen is generated on one side of the tube and monitored on the other side. The time for the hydrogen to reach the other side is used to determine the diffusion coefficient of hydrogen in the tube. Boundary conditions at the entry and exit sides have been investigated separately. Preliminary studies were performed on Stainless Steel 316 and Nickel Alloy 800 to better understand the influence of the solution chemistry on the electrochemical evolution of hydrogen. The surface phenomena effect and the trapping effect are discussed to account for differences observed in the permeation response. The hydrogen permeation through oxides at the exit side has been studied. Two nickel alloys (Alloy 800 and Alloy 600), materials widely used for steam generator tubes, have been investigated. The tubes ...

International Nuclear Information System (INIS)

CT is the most accurate method to detect pulmonary emphysema in vivo. They compared prospectively two different methods for emphysema quantitation in 5 normal volunteers and 20 consecutive patients with chronic obstructive pulmonary disease (COPD). All subjects were submitted to function tests and HRCT; three scans were acquired at preselected levels during inspiration. The type and extent of pulmonary emphysema were defined by two independent observers under blind conditions. Disagreements were subsequently settled by consent. All subjects were also examined with expiratory spiral CT using a density mask program, at two different cut-off levels (-850,-900 HU). Visual score and expiratory spiral density mask values (-850 HU) were significantly correlated (r = 0.86), but the visual extent of emphysema was always higher than shown by expiratory spiral CT. The emphysema extent assessed with both CT methods correlated with the function result of expiratory airflow obstruction and ...

International Nuclear Information System (INIS)

Thermo-reactive diffusion chromizing followed by pulsed plasma nitriding were carried out on AISI 52100 and 8620 bearing steels. The chromized samples were pulse-plasma nitrided for 5 h at 500 deg. C in various N_2-H_2 gas mixtures. The coated steels were characterized using scanning electron microscopy, X-ray diffraction and microhardness testing. The unlubricated wear behaviors of only chromized and duplex treated steels were investigated in ball-on-disc system tests at room temperature. X-ray diffraction patterns of the duplex treated samples containing H_2 indicated the formation of dominant CrN and Cr_2N nitrides as well as the formation of Cr_3C_2 and Cr_7C_3 carbides. Gas mixtures in the plasma nitriding, which was performed after chromizing, have a significant influence on the wear rate of the duplex treated steels. The wear and friction tests showed that the lowest friction coefficient and wear rates were observed ...

International Nuclear Information System (INIS)

Accurate modeling of the enhanced diffusion of boron during rapid thermal annealing has been accomplished by incorporating the effects of extended defect formation and annealing on enhanced diffusion into a multizone, semiempirical model. The multizone model divides the implant profile into three zones defining regions of different defects and diffusion enhancements. The model also contains the initial enhanced diffusion and the transient diffusion effects associated with the dissolution of defect clusters and the annealing of extended defects, respectively. The saturation time for transient-enhanced diffusion contains an exponential function of implant dose in order to model the increase in point defect generated with higher implant dose. As a result, the model accurately simulates the boron diffusion profile over a wide range of implant ...

International Nuclear Information System (INIS)

Transient enhanced diffusion in boron-implanted silicon is interpreted as being due to the fact that during rapid thermal annealing a relaxation process takes place, associated with quasi-chemical reactions including defects. A simple analytical model makes it possible to describe the annealing mechanism on a microscopic scale in terms of reaction-diffusion processes. The measured dependences of the boron diffusion coefficient of the enhanced diffusion on time, temperature and implantation energy are satisfactorily explained. (author).

Science.gov (United States)

The simultaneous diffusion of Si and the dopants B, P, and As has been studied by the use of a multilayer structure of isotopically enriched Si. This structure, consisting of 5 pairs of 120 nm thick natural Si and {sup 28}Si enriched layers, enables the observation of {sup 30}Si self-diffusion from the natural layers into the {sup 28}Si enriched layers, as well as dopant diffusion from an implanted source in an amorphous Si cap layer, via Secondary Ion Mass Spectrometry (SIMS). The dopant diffusion created regions of the multilayer structure that were extrinsic at the diffusion temperatures. In these regions, the Fermi level shift due to the extrinsic condition altered the concentration and charge state of the native defects involved in the diffusion process, which affected the dopant and self-diffusion. The simultaneously recorded ...

International Nuclear Information System (INIS)

Nickel cadmium batteries differ greatly in their mechanical design and construction of the electrodes. Using available electrode constructions, batteries are designed which meet the requirements of specific applications and offer optimum performance. Pocket- and tubular cells are basically developed with the technology of the year 1895. Since then some improvements with todays technology have been made. The sintered cells use the technology of the 1930's and they are still limited to high power application. With this knowledge and the technology of today the fiber-structured nickel electrode (FNC) was developed at DAUG laboratory, a subsidiary company of Mercedes-Benz and Volkswagen. After ten years of experience in light weight prototype batteries for electric vehicles (1-2), the system was brought into production by a new company, DAUG-HOPPECKE. Characteristics of fiber electrodes: thickness and size ...

International Nuclear Information System (INIS)

In the present paper we propose a model of physical phenomena behind the front face of the electrodes in an impulse plasma accelerator. The model is based on the results of recent experimental observations and measurements. It correlates plasma dynamics with mechanism of phenomena in a column of pinching plasma. On the contrary to the previous model the current one suggests the series of relatively short pulses of metallic ions from the erosion of electrode material. Till now the pinch was treated rather as a nearly continuous source of metallic plasma, feeding the process with ions from the erosion of electrode material. (author)

British Library Electronic Table of Contents (United Kingdom)

In this paper we describe a Ni-Sn intermetallic material obtained via template electroplating synthesis. The structure and the morphology of this material are investigated by X ray diffraction (XRD) and Scanning Electron Microscopy (SEM) analyses. We demonstrate that Ni-Sn behaves as a sub-micrometric electrode showing a favourable response when cycled in a lithium cell. The results here reported suggest that the template electroplating is a promising synthetic approach that can lead to an optimized structure and morphology of the Ni-Sn electrode, such as to confer it a role of a high capacity anode in advanced lithium ion batteries.

British Library Electronic Table of Contents (United Kingdom)

As portable electronics become more advanced and alternative energy demands become more prevalent, the development of advanced energy storage technologies is becoming ever more critical in today's society. In order to develop higher power and energy density batteries, innovative electrode materials that provide increased storage capacity, greater rate capabilities, and good cyclability must be developed. Nanostructured materials are gaining increased attention because of their potential to mitigate current electrode limitations. Here we report on the use of vertically aligned multi-walled carbon nanotubes (VA-MWNTs) as the active electrode material in lithium-ion batteries. At low specific currents, these VA-MWNTs have shown high reversible specific capacities (up to 782mAhg^-^1 at 57mAg^-...

KoreaScience (Korea)

Full Text Available

International Nuclear Information System (INIS)

... Moscow (Russian Federation) INIS-RU--495 385 p. INORGANIC, ORGANIC,

International Nuclear Information System (INIS)

Russian 1985. p. 114. USSR Levitskaya, GD Ture, MF Lata, LP L'vovskij

Energy Technology Data Exchange (ETDEWEB)

The present volume on modeling of batteries and fuel cells discusses the significance of the effectiveness factor for flooded porous electrodes, active pore distribution spectroscopy for characterizing porous battery electrodes, the agglomerate model for porous electrodes, and dynamic-performance measurements of battery cells for electric vehicles and other applications. Attention is given to mathematical modeling of a primary zinc/air battery, mathematical modeling of Grace Li-TiS2 cells, modeling of electrocrystallization processes in battery systems, and rotating disk electrode studies in molten Li/K carbonate eutectic. Topics addressed include the variability of nickel oxide cathode dissolution in molten carbonate fuel cells, water transport properties of fuel cell ionomers, modeling water content effects in polymer electrolyte fuel cells, and computer algebra applied in electrochemistry and fuel ...

Science.gov (United States)

... thus can function as switches -6 ... Akkari, "Optical Channel Waveguide Switch and Coupler ... Wide-Band Guided Wave Acousto-Optic Bragg Diffraction ...

British Library Electronic Table of Contents (United Kingdom)

In this work, a highly-sensitive polymeric membrane ion selective electrode for determination of tetracycline was constructed by using molecularly imprinted polymer (MIP) particles as quasi-ionophore. The water-compatible MIP particles targeting tetracycline were synthesized with tetracycline as a template molecule, methacrylic acid as a functional monomer, ethylene glycol dimethacrylate as a cross-linker, 2,2?-azobisisobutyronitrile as an initiator and lanthanum ion as a mediator. Benefited from the distinctive performance of the quasi-ionophore and the optimized composition of the membrane and the inner filling solution, the lower detection limit of the electrode was decreased to about 1 ? 10?8 mol/l. It exhibited a good electrode slope 59.8 mV/decade near the theoretical Nernstian one, ...

International Nuclear Information System (INIS)

Portuguese 2008 2 p. Brazil Silva, Diogo Lima da Andrade, Leonardo

International Nuclear Information System (INIS)

It is well known that a protective film is formed on the graphite negative electrode in ethylene carbonate (EC) electrolyte solution. This film is lithium-ion conductive and protects the decomposition of the electrolyte solution. In the present paper, the electrode/electrolyte interfaces in lithium-ion rechargeable batteries were characterized by three-dimensional complex impedance plots, whose axes are real, imaginary parts and time. The film resistance R _s_e_i and charge transfer resistance R _c_t were determined for negative electrodes in EC/ethyl methyl carbonate (EMC) electrolyte solution, and the formation mechanisms of the interfacial film were discussed. Furthermore, the contributions of vinylene carbonate and ethylene sulfite, which are added into the electrolyte solution for the film formation, were investigated.

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A dielectric-wall linear accelerator is improved by a high-voltage, fast rise-time switch that includes a pair of electrodes between which are laminated alternating layers of isolated conductors and insulators. A high voltage is placed between the electrodes sufficient to stress the voltage breakdown of the insulator on command. A light trigger, such as a laser, is focused along at least one line along the edge surface of the laminated alternating layers of isolated conductors and insulators extending between the electrodes. The laser is energized to initiate a surface breakdown by a fluence of photons, thus causing the electrical switch to close very promptly. Such insulators and lasers are incorporated in a dielectric wall linear accelerator with Blumlein modules, and phasing is controlled by adjusting the length of fiber optic cables that carry the laser light to the insulator surface.

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SLPL molecule to stimulate sufficient growth to have nerve sprouts enter the electrode and establish a neural interface for prosthesis control. ...

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This report describes the design of, and image reconstruction capacity of a Hadamard Raman Microscopic imager. Microscopy of benzoic acid and graphite electrodes, as well as electrophoretic blotting, are described. (CBS)

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We present a new approach for growing Si nanowires directly from a silicon substrate, without the use of a metal catalyst, silicon vapor or CVD gasses. The growth can be performed in a furnace type configuration at moderate temperatures or in localized regions by resistive heating. Since the silicon wires grow directly from the silicon substrate, they do not need to be manipulated nor aligned for subsequent applications. Wires in the 20-50 nm diameter range with lengths over 80 ?m can be grown by this technique. We have studied the effects of various growth parameters, including temperature, substrate orientation, initial sample cleaning and carrier gasses. Results indicate that most important parameters in the growth of the nanowires are the surface cleaning, the temperature and the type of carrier gas used. A model is proposed, which involves an oxide catalyst for the process, with the growth of the nanowires enabled by a significantly enhanced silicon surface ...

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We investigate the relationship between spiral arms and star formation in the grand-design spirals NGC 5194 and NGC 628 and in the flocculent spiral NGC 6946. Filtered maps of near-IR (3.6 #mu#m) emission allow us to identify 'arm regions' that should correspond to regions of stellar mass density enhancements. The two grand-design spirals show a clear two-armed structure, while NGC 6946 is more complex. We examine these arm and interarm regions, looking at maps that trace recent star formation-far-ultraviolet (GALEX NGS) and 24 #mu#m emission (Spitzer SINGS)-and cold gas-CO (HERACLES) and H I (THINGS). We find the star formation tracers and CO more concentrated in the spiral arms than the stellar 3.6 #mu#m flux. If we define the spiral arms as the 25% highest pixels in the filtered 3.6 #mu#m images, we find that the majority (60%) of star formation tracers occur in the interarm regions; this result persists qualitatively even when considering the potential impact ...

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An experimental study of H-air counterflow diffusion flames (CFDFs) is reported. Coaxial tubular

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Thermal (gas) nitridation of stainless steel alloys can yield low interfacial contact resistance (ICR), electrically conductive and corrosion-resistant nitride containing surface layers (Cr{sub 2}N, CrN, TiN, V{sub 2}N, VN, etc.) of interest for fuel cells, batteries, and sensors. This paper presents results of proton exchange membrane (PEM) single-cell fuel cell studies of stamped and pre-oxidized/nitrided developmental Fe-20Cr-4V weight percent (wt.%) and commercial type 2205 stainless steel alloy foils. The single-cell fuel cell behavior of the stamped and pre-oxidized/nitrided material was compared to as-stamped (no surface treatment) 904L, 2205, and Fe-20Cr-4V stainless steel alloy foils and machined graphite of similar flow field design. The best fuel cell behavior among the alloys was exhibited by the pre-oxidized/nitrided Fe-20Cr-4V, which exhibited {proportional_to}5-20% better peak power output than untreated Fe-20Cr-4V, 2205, and 904L metal stampings. ...

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Photoelectrochemical oxidation is a potentially interesting method for destroying toxic organic materials. We have studied the photoelectrocatalytic activity of TiO{sub 2} films made by thermal oxidation of titanium, low pressure chemical vapour deposition (LPCVD), and anodisation of titanium. Two model organic compounds have been investigated for photooxidation: methyl phosphonic acid (MPA) which is a nerve gas analogue and 4-chlorophenol (4-CP) which is a chlorinated aromatic compound considered a standard for the evaluation of the TiO{sub 2} / UV processes. In addition to photoelectrochemical characterisation the films have been characterised by profilometry, XRD, AFM, photocurrent spectroscopy and Raman microscopy. Correlations have been made between the physical properties of the thin films and their catalytic activities. The most catalytic sample of thermally oxidised titanium was prepared at 400 deg C, and the presence of anatase was shown by XRD, MPA ...

International Nuclear Information System (INIS)

The thermo-chemical treatments of steels with plasma is normally carried out in low-pressure ionized gaseous atmospheres. Among the treatments used most often are: nitruration, carburization and boronized. A plasma can also generate at atmospheric pressure. One way to produce it is with an electrochemical cell that works at a relatively high inter-electrode voltage and under conditions of heavy gas generation. This type of plasma is known as electrolytic plasma. This work studies the feasibility of using electrolytic plasma for the surface processing of steels. Two processes were selected: boronized and nitruration., for the hardening of two types of steel: one with low carbon (1020) and one with low alloy (4140). In the case of the nitruration, the 1020 steel was first aluminized. The electrolytes were aqueous solutions of borax for the boronizing and urea for the nitruration. The electrolytic plasmas were classified qualitatively, in relation ...

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Numerical models based on finite-difference or finite-element methods are used by various research groups in studies of radon-222 transport through soil and building materials. Applications range from design of radon remediation systems to more fundamental studies of radon transport. To ascertain that results obtained with these models are of good quality, it is necessary that such models are tested. This document reports on a benchmark test organized by the EU project ERRICCA: European Research into Radon in Construction Concerted Action. The test comprises the following cases: 1) Steady-state diffusive radon profiles in dry and wet soils, 2) steady-state entry of soil gas and radon into a house, 3) time-dependent radon exhalation from a building-material sample. These cases cover features such as: soil heterogeneity, anisotropy, 3D-effects, time dependency, combined advective and diffusive transport of radon, flux ...

International Nuclear Information System (INIS)

Marker experiments for studying the mass transport through a palladium silicide layer on a crystalline substrate during thermal oxidation at 700 to 850 deg C have been reported recently. In this work argon gas embedded in amorphous silicon during sputtering was implemented as the inert marker and the oxidation of PdSi was processed above 900 deg C. At this high-temperature oxidation silicon-rich silicide PdSisub(y), with y exceeding 5, may be obtained. This can be anticipated by considering the Pd-Si phase diagram which shows the liquid phase may appear at an annealing temperature above 892 deg C. As a result, a non-stoichiometric and non-uniform silicide layer may develop at the sample surface. Marker analysis showed that both palladium and silicon dissociated at the Pdsub(x)Si/ SiO_2 interface and moved to the substrate with the silicon being the dominant diffuser. The Rutherford backscattering spectra (RBS) showing the oxide film and ...

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Under typical conditions found in Pressurized Fluidized Bed Combustion (PFBC), the calcination reaction of limestones is thermodynamically inhibited, and the sorbent reacts with SO{sub 2} by a direct mechanism. Direct sulfation reactivity of different Spanish sorbents was studied by high-pressure thermogravimetric analysis. It was found that the physical structure of the surface of the particles influence the sulfation behaviour of the sorbents. Total pore volume and pore surface area correlated well with the reactivity of the sorbents. Temperatures between 800 and 925{degree}C, and pressure between 12 and 25 bar, promoted an increase in reactivity, while the gas composition had no effect when changed from 15% CO{sub 2}, 3% O{sub 2}, 0.5% SO{sub 2}, balance N{sub 2} to 12% CO{sub 2}, 7% O{sub 2}, 0.5% SO{sub 2}, balance N{sub 2}. It was found that the unreacted shrinking core model could not satisfactorily describe the sulfation reaction under the conditions ...

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Combustion scientists are primarily concerned with the fuels most often burned as energy sources (coal, petroleum products, and natural gas), with the goal of learning to burn them as efficiently, intensely, and cleanly as possible. Discovering those slight rearrangements of chemical bonds that together account for the net chemical transformation is the key to understanding how combustion proceeds. Once these reactions have been defined, the chemist can determine the rate coefficient of each reaction as a function of temperature and assemble the information into flame models. The computer programs that use these models to predict experimental results combine two sets of equations describing (1) the diffusive and reactive rates of change in concentration of all the molecules in the flame and (2) the flow of the reacting gases. Although the details of hydrocarbon-flame models are still disputed, many of their general features are clear and the ...

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An investigation was conducted into alternative techniques for zinc and electrolyte regeneration and reuse in the refuelable zinc/air battery that was developed by LLNL and previously tested on a moving electric bus using cut wire. Mossy zinc was electrodeposited onto a bipolar array of inclined Ni plates with an energy consumption of 1.8 kWh/kg. Using a H{sub 2}-depolarized anode, zinc was deposited at 0.6 V (0.8 kA/m{sup 2}); the open circuit voltage was 0.45 V. Three types of fuel pellets were tested and compared with results for 0.75 mm cut wire: spheres produced in a spouted bed (UCB); coarse powder produced by gas-atomization (Noranda); and irregular pellets produced by chopping 1-mm plates of compacted zinc fines (Eagle-Picher, Inc.). All three types transported within the cell. The coarse powder fed continuously from hopper to cell, as did the compacted pellets (< 0.83 mm). Large particles (> 0.83 mm; Eagle-Picher and UCB) failed to feed from ...

International Nuclear Information System (INIS)

1 - Description of program or function: This library for fusion neutronics calculations, to be used in conjunction with the TRANSX code, is the MATXS format version of ZZ-GEFF-2-GENDF from which it has been derived by means of the MATXSR NJOY module. It has a 175 neutron, 42 photon VITAMIN-J group structure with the standard weighting function: Maxwellian (at the temperature to which the material is referenced) + 1/E + fission spectrum + 1/E + fusion peak + 1/E. It includes 93 materials from 1-H-1 to Bi-209 - almost all from EFF-2 basic data; but Ag-107, Ag-109, natural Cd, the 6 Hf isotopes and the 4 W isotopes have been taken from JEF-2.2 - at 3 temperatures and 6 dilution cross section values; 10 thermal groups are provided below 3 eV. Neutron cross sections and diffusion matrices, photon and gas production, kerma and DPA are given. The library includes H in H2O, metallic Be and Graphite for which an accurate treatment with S(alpha, beta) ...

Science.gov (United States)

In a redox battery using a titanium redox system or chromium redox system as an active material for the negative electrode or a manganese redox system as an active material for the positive electrode, the electromotive force of the battery and the stability of electrolyte solutions are enhanced by addition of a chelating agent such as citric acid or a complexing agent such as phosphoric acid to the redox system used therein.

International Nuclear Information System (INIS)

The electrochemical treatment of solutions containing C.I. Basic Yellow 2 (BY2) in aqueous solutions with carbon-PTFE (polytetrafluoroethylene) and carbon nanotube (CNT)-PTFE electrodes as cathode has been studied. The fabricated electrodes were characterized by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The amount of electrogenerated H2O2 on the surface of these electrodes was investigated, too. The results showed that the amount of H2O2 obtained with the CNT-PTFE electrode was nearly three times higher than that of carbon-PTFE electrode. The decolorization efficiency of BY2 in peroxi-coagulation process reached 62% and 96% in the first 10 min by carbon-PTFE and CNT-PTFE electrodes at 100 mA, respectively. The effect of operational parameters such as applied current, initial pH and initial dye concentration was studied in an attempt ...

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According to the invention, a zinc foil is arranged between the negative electrode of a zinc/air battery (round cell) and the expansion space compensating for the reactive increase in volume of the zinc powder. This zinc foil functioning as a stop diaphragm particularly ensures, from the very onset, that the zinc filling has a density and compactness necessary for good electronic conductance.

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Chlorophyll-a (Chl-a) assembled in hydrophobic domain by fatty acid with long alkyl hydrocarbon chain such as myristic acid (Myr), stearic acid (Ste) and cholic acid (Cho) modified onto nanocrystalline TiO{sub 2} electrode is prepared and the photovoltaic properties of the nanocrystalline TiO{sub 2} film by Chl-a are studied. Incident photon to current efficiency (IPCE) value at 660 nm in photocurrent action spectrum of Chl-a/Ste-TiO{sub 2}, Chl-a/Myr-TiO{sub 2} and Chl-a/Cho-TiO{sub 2} electrodes are 5.0%, 4.1% and 4.1%, respectively. Thus, the IPCE is maximum using Chl-a/Ste-TiO{sub 2} electrode. From the results of photocurrent responses with light intensity of 100 mW cm{sup -2} irradiation or monochromatic light with 660 nm, generated photocurrent increases using Chl-a/Ste-TiO{sub 2} electrode compared with the other Chl-a assembled TiO{sub 2} electrodes. These results show that ...

International Nuclear Information System (INIS)

Contrary to the electronic excitation induced phenomena of desorption and sputtering, we observed incorporation of oxygen in a thin Fe film during its irradiation with swift heavy ions. It is observed that the adsorbed oxygen diffuses in to the Fe film. The incorporation of oxygen and its diffusion in the bulk of the film is a manifestation of extremely large electronic energy deposition by the incident ions. It is shown that the experimentally observed high diffusivity of oxygen in Fe during irradiation is due to the existence of transient melt phase of Fe.

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Norwegian Open Research Archives (NORA)

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PMID:20602289

Energy Technology Data Exchange (ETDEWEB)

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CERN Document Server

voltammetric methods. This remained evident for varying extents of silver dissolution. Ag(111) electrodes were oxidised in 0.1 M KCIO sub 4 solutions by a single swept ORC of 0.77x10 sup - sup 3 C cm sup - sup 2. The final rest potential of the Ag(111) working electrode was over the potential range of -36 mV to 114 mV versus the SCE where the silver islands of the reformed surface are believed to be unstable. Results show that a majority of silver islands of all sizes are stable with time, whereas the silver islands with irregular shapes tended to evolve to exhibit higher degrees of spherical geometry. Additionally, the position of the silver islands did not remain constant during the acquisition of STM images. Results from in situ STM demonstrated that the underlying step-terrace morphology of the Ag(111) electrodes did not remain constant with time. Both macroscale and nanoscale changes to the Ag(111) ...

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Carbons derived from the phase separation of polyacrylonitrile/solvent mixtures were investigated as lithium intercalation anodes for rechargeable lithium-ion batteries. The carbon electrodes have a bulk density of 0.35-0.5 g/cm{sup 3}, relatively low surface areas (< 10 m{sup 2}/g), and micron-size cells. Pyrolysis temperature influences the reversible lithium intercalation and the irreversible capacity (associated with the formation of the passivating layer). Carbon electrodes pyrolyzed at 600{degrees}C have first-cycle capacity as high as 550 mAh/g as well as large irreversible capacity, 440 mAh/g. Electrodes prepared at 1050{degrees}C have reversible capacities around 270 mAh/g with relatively lower capacity losses (120 mAh/g). Doping the organic precursors with phosphoric acid, prior to pyrolysis at 1050{degrees}C, leads to carbon electrodes with reversible capacities as high as 450 mAh/g. The ...

International Nuclear Information System (INIS)

Radon appears mainly by diffusion processes from the point of origin following #alpha#- decay of "2"2"6Ra in underground soil and building materials used, in the construction of floors, walls, and ceiling. The transport phenomenon of radon through diffusion is a significant contributor to indoor radon entry. In the present study radon diffusion through sand, cement, mixtures of sand + cement (1:1), sand + cement (2:1), sand + cement (3:1), sand + cement (4:1) has been carried out using LR-115 type II solid state nuclear track detectors (SSNTDs). The radon diffusion coefficient and diffusion lengths have been calculated for different materials. The effect of compaction, which changes the porosity and permeability of the materials, on radon diffusion has also been studied. (author)

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We have investigated the diffusion of Sb in Si in the presence of defects injected by high-energy implantation of Si ions at room temperature. MeV ion implantation increases the concentrations of vacancies, which induce transient-enhanced diffusion of Sb deposited in Si. We observed a significant enhancement of Sb diffusion. Secondary ions mass spectroscopy has been performed on the implanted samples before and after annealing. Rutherford-backscattering spectrometry has been used to characterize the high-energy implantation damage. By fitting diffusion profiles to a linear diffusive model, information about atomic scale diffusion of Sb, i.e. the generation rate of mobile state Sb and its mean migration length were extracted.

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International Nuclear Information System (INIS)

For the purpose of optimizing the process of co-implantation of MeV Si ions to reduce boron transient enhanced diffusion and boron-enhanced diffusion in Si, multiple MeV implantations and annealing at different temperatures have been performed. A slight improvement on the suppression of B diffusion is observed by adding a low temperature annealing step after the MeV implantation. No differences in B diffusion are observed when the Si doses are increased from 1 x 10"1"5 to 1 x 10"1"6 cm"-"2. This dose independent behavior is speculated to be a quasi-steady state of vacancy cluster evaporation.

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An embodiment of a mercury-free fluorescent lamp combines a low pressure rare gas discharges with a phosphor having a quantum efficiency grater than one. The choice of the rare gas depends on a number of factors, one of which is the resonance transition energy. Less demand is placed the quantum efficiency of the phosphor for a lower energy resonance photon. Xenon has the lowest energy resonance transition of the stable rare gases at 8.5 eV (147 nm) and thus is a good candidate to study. The usefulness of a xenon-based discharge depends on the radiant emittance of the discharge at the resonance wavelength of 147 nm. The radiant emittance from a low pressure xenon positive column discharge is measured using two independent techniques. The first relies on the measurement of the resonance level density using absorption techniques. The effective decay rate of the resonance level is calculated using radiation trapping theory. The product of this ...